In the mid-19th century, the French architect and lithographer Alfred Guesdon (1808-1876) travelled through Spain creating panoramic views of several Spanish cities. He did this by taking flights in hot-air balloons and then making various daguerreotypes from the air with the utmost caution (photography as we know it only began to be used some years later). These aerial photographs produced images of varying clarity which he used as a basis for his drawings, which he then made into very realistic lithographs.
The result of one of these is the view of the Santa Maria district in Madrid, today known as Cuesta de la Vega. This shows the state of the Cuesta de la Vega hill before the urban reforms carried out in the early 20th century.
By enlarging the view we can make out a horse-drawn carriage going up the steep slope at the top of the Cuesta de la Vega, at that time newly remodelled, next to the wall separating the street from the barracks of the Royal Guards. The Palace Carriage House can be seen clearly, and a spacious enclosed courtyard which runs alongside a wall dividing it from the gardens of what was then the Royal Footmen's House. Above this courtyard is a small building which appears to be somewhat out of place among the other buildings; it is situated in the centre at a higher level, and is reached by a ramp.
All these areas are buried under the foundations of the Almudena Cathedral and the surrounding lands which are currently being excavated for the proposed Carriage Museum; and they all lie at a depth of no more than ten or twelve metres, as can easily be seen.
What is today known to be demonstrably true stems from the publication in 1939 by the Hispanic scholar Levy-Provençal in Holland. The translation of a previously unknown text by al-Himyari, who lived in the 13th and early 14th centuries, established, among other things, the origin of Madrid as an Arab "ribat", or fortress, between 885 and 887 by Mohammed I; the news was met with indifference by historians of Madrid, despite its publication some time later by the newspaper ABC.
Years later people began to take an interest in the origins of the city, and although it was assumed that there had been Visigothic settlers before the construction of the Ribat, there was no definitive proof of their existence. Some historians believe that this might have been primarily a rural community which settled near the lakes existing at the time in Puerta Cerrada. Water from these lakes may have flowed down today's Calle de Segovia to what is known as the Arroyo de San Pedro stream, although there is no documentary proof for this hypothesis.
In 1972 and 1987, trial archaeological excavations were carried out in the lands which appear in the panoramic view, and there are records of a chamber located beside the South Tower of the former Puerta de la Vega gate in the Arab walls. This existence of this chamber was already known as it was used as an anti-aircraft shelter in the Spanish Civil War, and was regularly visited by the police responsible for the city's below-ground installations.
The chamber is described as a construction measuring nine metres in length by five metres high, with two doors, one with a lower arch facing north, and the other on the opposite side facing the Cuesta de la Vega hill. The chamber runs on a north-south axis, and is divided in two by a large granite wall; it has a vaulted ceiling and is lined in brick with simple decorative motifs. The decorative stone elements on the lateral walls are blind arches, crowned with brick capitals at the base of the vaulted ceiling. The floor is made of flint slabs and is partially deteriorated, revealing former floors which have also been seriously damaged by damp. There is a deep indentation visible on the floor which resembles the imprint made by a baptismal font.
All these areas are buried under the foundations of the Almudena Cathedral and the surrounding lands which are currently being excavated for the proposed Carriage Museum; and they all lie at a depth of no more than ten or twelve metres, as can easily be seen.
Professor Manuel Montero Vallejo from the Institute of Madrid Studies affirmed in 1987 that this chamber had served as lodgings for the Guard Corps which controlled the entry through the gate in the city walls.
In 1992, the town council's Public Works manager, Mr. Luis Armada, published a report by municipal technicians and archaeologists in which they reached the conclusion that the chamber may have been built between the 7th and 10th centuries. This theory was based on the dimensions of the bricks, the configuration of the blind arches and the shape of the edges of the vaults.