Santa María de la Granada mosque-church was also declared Architectural-Artistic Monument by the Republic's government together with other buildings of the province of Huelva, dated the 4th of June of 1931 and published in the Gaceta de Madrid of that date, num155. 
During the dictatorship of general Franco, Niebla castle and walls were declared Architectural-Artistic Monument by decree of 14th of April of 1945; such order was published in the Boletín Oficial del Estado on the 20th April. Historical-Artistic Ensemble proceedings dated the 5th of September of 1979 were started by a resolution of the General Direction of the Artistic-Historical Patrimony and Museums,
Nevertheless, until 1982, when Historical-Artistic Ensemble of the town of Niebla proceedings were started, these actions were not effective enough for the legal body and regulations they were based on were too varied. Since the powers were transferred to the Autonomous Government of the Junta de Andalaucía, the Historical-Artistic Ensemble of the town of Niebla is under protection of the Historical Patrimony of Andalucía Law, dated the 3rd of July of 1991.  
Protohistoric Enclosures: The finding of the location of at least two pre-Roman enclosures is an important achievement of the archaeological research carried out in this area. The most ancient one is on the Desmbarcadero area as a rubblework sloping wall resting on the sterile calcareous substratum, which forms a balcony over the river. A monumental base with huge stone blocks and rubblework was built upon the former wall between the oriental and the turdetano periods to make the former wall thicker, as a sloping retaining wall. At the top of that wall, it has been documented the continuation as a deffenssive wall of casamatas ( great resistance vault) on the calcareous substratum has been documented, maybe in all the perimeter. This defensive wall seems to have oriental antecedents. Both walls represent one of the most interesting examples of the poliorcética of the 9th-5th centuries B.C., maybe the best preserved example in the peninsular south-west. 
The Roman enclosure: There are no important visible traces of the Roman enclosure, which was referred to in the classical sources as Ilipla, parvum oppidum. Nevertheless, there are some proofs of its existence, such as dressed blocks of stone of Roman style in the base of the Puerta de Sevilla, the Roman remains where an adobe wall is resting in an area called Callejón de la Ollita, and the documentaed remains of a street formerly called Calvo Sotelo.. This enclosure will be excavated in future scheduled archaeological works. As far as we kow now, this Roman wall must have been made of assembled blocks of stone and rubblework, with solid towers at regular intervals. The first muslim wall enclosure (¿Califal?): Most of this enclosure is visible in the Desembarcdero area, made of blocks of stone, upon which we can see superimposed parts of adobe wall, belonging to a later enclosure. Part of the stone covering of the area located in the sloping wall facing the river, has disappeared, exposing to view the archaeological levels of this period. The Medieval walls: They are built upon the former wall of blocks of stones, remaining the whole perimeter, except for the nort-west angle, where the alcazaba would be pulled down in order tobuild the christian alcázar and its barbican. As a result of the capture of the town by Abú-Zacarya ben Yuma in 1154, the enclosure was considerably damaged; so, it was necessary to repair it, or to plan the construction of a new one during the almohade period. 
Anyway, due to the lack of research, there is doubt that new enclosure of adobe wall was built in the almorávide period and it was only remodelled in the almohade period; it is difficult to get to know which part corresponds to each period, and more recent research even suggests that a big part of the enclosure could have been built in times of Ibn-Mahfoh. There is no doubt that the corner gates, such as Puerta de Sevilla, del Agua, del Buey, del Socorro or del Desembarcadero, have been built according to the almohade poliorcética techniques of the 13th century, as documented in other hispanic-muslim cities (GONZALO,1986). It is mainly built as an adobe wall enclosure with blocks of stones and bricks where necessary, resting upon the calcareum substratum, upon foundations built for that purpose on prior archaeological formations, or even upon prior wall strutures. Forty-six advanced square towers and two octagonal towers were built along the enclosure; five corners gates were also built in brick and block of stones, from former buidings in many cases. In the north area facing the arrabal a small gate called del Agujeo was built, as well as two openings that were made in the enclosure beside the Puertas del Buey and del Socorro, and another one in the outer section of the Puerta de Sevilla, in order to ease the road traffic into the town. An alcazaba located in the same place as the Alcázar de los Guzmán is nowadays, completed the defenssive perimeter of the fortress . There are no data available proving that the muslim alcazaba was repaired after the conquest of the town by Alfonso X in 1262, but in the following century it was still standing, for in 1320 it would be took by storm by the town's oligarchy to oust the new governors appointed by the infant Don Felipe, tutor of Alfonso XI.  
Ater the works of restoration made in the last few years, the Alcázar is nowadays in good conditions. It has a rectangular structure divided by an inner wall which separates the patio of arms from the luxurious rooms intended as palace. This main structure has ten towers; six of them are square (four are on the corners -including the Tower of Homage- and two of them are at the ends of the inner wall). The other four are semicircular cubes alternated with the square ones. The walls go on from the Tower of Homage and the one located on the north-west angle to form a barbican surrounding the central building on the east, south and west sides. This barbican has six towers and joins the almohade wall near the Puerta de Sevilla and del Socorro. An adarve and a barbican built in the late 15th century completed the building. The construction of the alcázar started in 1402, when Don Enrique de Guzmán, the second Duke of Medinasidonia and the fourth of Niebla, pulled down the old alcázar and to build the one we know today. The result was a magnificent royal palace which preserved the most interesting and luxurious parts built by the arabs, such as the muslim Tower of Homage, which was rebuilt so magnificently that was compared to the Giralda tower of Seville (today it is called Murete de la Reina). The alcázar had a magnificent gate of "florido"gothic style, crowned by the famiily coat of arms, bordered with lions and a castle. The most outstanding features are the beautiful balconies with gothic sills and the exquisite work of a railing in the upper part which is very similar to that of El Cordón (noble house of Burgos) and the Huelgas Monastry (MARÍN,1982) 
So, this is indeed a monumental work, maybe the most important of the 15th century, which proves the wealth and importance of the Guzmán's lineage and the familily's intention of making the town fit the social relevance of their position. The main constructive element is the local stone and it is remarkable the work of ashlars( some of them belonging to former constructions) of the lower parts of walls and towers. The structure may seem austere today, for the upper parts, which were more richly decorated, have not remained. Neverteheless, the troneras (small windows) ornamented with the cross and the orb -typical element of Guzmán's palaces and houses- are still outstanding nowadays. According to a document of the early 17th century about the alcázar, some works were necessary to restore the building to its former glory.This document is a very important proof to know the building's layout; in the palace area, non-existent today, a building rose with a central courtyard with archades around which were located the bedrooms, a room for the administration of justice, a dining-room, kitchens, etc. It was specially outstanding the golden half orange room, called so because of its Mudejar coffered ceiling, and where the Earl would administer justice and receive dignataries and vassals. 
It is also interesting to note that, in this document, it is not clearly mentioned the section of the barbican that today closes the perimeter of the alcázar on its sides north and west; so it must have been built later, maybe during the war against Portugal, for this new barbican with a quebrada ground plan and sloping walls is built according to the rules of the poliorcética , architectural technique conceived according to the defensive needs created by the new artillery arms of the 17th century, and that can be seen in the border fortresses built to the east of the Guadiana river. In its layout appear two cellars, the first one to keep artillery arms and the second one to be used as a storeroom, and which would be partially hidden under the ground, or in front of a ditch that completed the defensive infrastructure of the alcázar. The new works of restoration would allow to locate in them part of the Gunpwder Town Museum. One of the most outstandings elements of the fortress is the big size of the base of its Tower of Homage, which with good reason was considered to be the second of Andalucía in height before its destruction by an earthquake in 1755 and the damage caused by French troops in 1812. Marshal Soult had converted the town into a strongpoint. When the town was besieged by General Lacy, who was in the service of the Spanish crown, the French troops blew up the arsenal they had placed in the town, causing important damage to the fortress (AMADOR DE LOS RÍOS,1891)  It is one of the buildings with the most transformations of the town legacy. An in-depth study of this church has never been made, but its location in one of the most strategical locations of the town, and its remains, are important keys to knowing its evolution throughout the History. 
In the decade of the 1920s of the 20th century, as it was in ruins and without cult, part of it was pulled down in order to ease the road traffic circulation, so that only part of the apse at the front part of the church and the original central gate at the bottom remain; the central part of the three christians naves and the transept were in good conditions in the late 19th century, as showed in a photograph published by Amador de los Ríos, but they disappeared in the partial demolition of the 1920s. The paleochristian and visigothic remains embedded in its walls made Amador de los Rios consider the existence of a primitive christian church on that site, maybe the episcopal see of the Visigothic Elepla. That assumed building would have been used for the construction of one of the main mosques of the muslim Labla, with five naves and almina. The conversion of the building to the christian cult after the conquest, with Latin cross plan and a beautiful masonry apse, would have involved considerable changes in its appearence: the complete or partial demolition of its assumed five naves, the conversion of the alminar into a bell tower, the increase of its height, the blocking off of the doors, etc. 
The remaining door at the bottom of the central nave is made of bricks and has the typical muslim shape: double horseshoe arch on marble macelas, alfiz and borders with lacería pattern ( geometrical decoration consisting of interlaced lines forming star-shaped and poligonal figures). The comparison of that door with other ones of the peninsular south leads to think that it is maybe a mudejar work of the 14th century, subsequent to the christian conquest. According to the photographs of the late 19th century referred to above, the church would have three naves, with the central one on an upper level than the lateral ones. The fact that the naves have pointed horseshoe arches could lead to date them about the 1400. 
The apse, the most monumental part of the church, is not common in the onubense gothic style. Nevertheless, it has a polygonal plan of twelve sides and its vault has no espinazo rib (the rib that links the arches' keystones going through the vault's keystone), which is a typical feature of Seville's and Huelva's Gothic style. There are some parallels with Seville's cathedral , according to which the apse could date from the first quarter of the 15th century. The architectural history of this church could possibly be reconstructed as follows:
 
Two opposing styles unite in this building, endowing it with a special beauty, in spite of its austerity. 
The former building was a mosque, maybe with five original naves and a subsequent sixth one, and an alminar.A big part of the side walls from this period remain, as well as the mihrab in the quibla wall and another opening where the alminbar ( a mobile wooden pulpit for the preacher)was kept. The starting point of the arches leading to the sahn, the oriental galleries and the canes supporting the eaves of the roof, also remain from this time.  After the christian conquest, the alminar was firstly elevated and buttressed so that it could stand the bells' weight by covering the former structure. Subsequently, maybe in the 15th century, the arches of the middle naves were pulled down to build a higher three aisled church, and a large gothic-mudejar apse with a star-shaped ribbed vault, that would be completed in 1515. During the Spanish Civil War a remarkable mudejar coffered ceiling burnt up.  
It is very near Santa María church. The chapel with square ground plan presbytery remains from an early stage of construction, maybe in the 14th century. The presbytery has a ribbed vault made of brick, even though the reinforcing arches and the formeros arches (the arches parallel to the longitudinal axis of the nave) are made of regular shaped blocks of stones. 
The main arch is pointed and has the typical gothic moulding. It opened to an only nave with mudejar par y nudillo coffered ceiling. On the right there was another nave that does not exist today, where a neclassical colister was located. In the 17th and 18th centuries, the building was enlarged, although the former medieval modules were repeated. The hospital in the strict sense was pulled down and two rooms were built, maybe making the original courtyard bigger, and some openings were left as windows. The exterior of the building was substantially changed, so that it is not possible to get an idea of the primitive construction from it. A espadaña (high wall at the top of the façade used as a bell tower) of Baroque style was built on the façade at the third floor level. It was ornamented with arches framed by pilasters superimposed on the former portal of isabelino style of the 15th century, which had a Tudor arch (a type of arch typical of the late Gothic) in emplantillado brick.  
This is a bridge of Roman origin, as it follows from a superficial analysis of some of its parts, even though some of them have been reconstructed in later periods, even in the 20th century after its blowing up during the Spanish Civil War. Part of its materiales were re-used and new arches were laid out because of the collapse or ruin of the original ones. It is remarkable the presence of Roman elements still visible in the east area, which remain as a whole. There are semicircular arches with very big arch-stones perfectly laid out. These other arches belong to muslim and later reconstructions, although they are semicircular or pointed. |
ue to the monumental importance of Niebla,during the 20th century, successive government administrations have endowed the town with a wide legal base for the preservation and protection of its patrimony. The remains of San Martín church were declared Arquitectural-Artistic Moument by Royal Order of the king Alfonso XIII, as published in the Gaceta de Madrid, num. 333, dated 29th November 1922.
and a declaration of the Ensemble by Royal Decree 559/1982 of 1st February of 1982 was published in the Boletín Oficial del Estado, dated the 18th of March of the same year.