later Pre-Romanesque churches. The church of San Tirso, located beside the Cathedral of Oviedo, conserves only the end wall of the apse from its original construction, because it was destroyed by fire in the 16th century. The section remaining shows the original construction in stone blocks, and in the centre, there is the characteristic three-point window of Asturian Pre-Romanesque, with semicircular arches made of brick. The central opening, larger than the side ones, is supported by free-standing columns. The Holy Chamber was built as a palace chapel for Alfonso II and the church of San Salvador (both demolished in the 14th century to build the present Gothic cathedral). The Chamber, adjoining the pre-Romanesque Tower of San Miguel, also had the function of housing relics brought from Toledo after the fall of the Visigothic kingdom. It consists of two overlapping aisles with a barrel vault; the crypt or lower floor has a height of 2.30 metres, and is dedicated to St. Leocadia, containing several tombs of other martyrs. The upper floor, dedicated to St. Michael, was extended in the 12th century, elongating the central section to six metres, a reconstruction that also provided it with its current decoration, a masterpiece of Spanish Romanesque. From an architectural point of view, the Holy Chamber's construction solved one of the greatest problems of Asturian Pre-Romanesque: the vaulting of two overlapping spaces, later used in the buildings of Ramiro I. As mentioned above, acting as a royal chapel, the Holy Chamber was built to house the jewels and relics of the cathedral of San Salvador in Oviedo, a function it continues to have 1,200 years later. Some of these jewels were donated by the Kings Alfonso II and Alfonso III, and represent extraordinary gold artefacts of Asturian Pre-Romanesque. The first of them is the Cross of the Angels, created in 808 in Gauzón (the left bank of the estuary of Avilés) on the instructions of Alfonso II of Asturias, who donated the precious stones necessary to make it from his personal treasury. The Cross of the Angels takes its name from the legend that it was made and given to Alfonso II by angels, who appeared to him in the form of pilgrims. The Greek cross (equal arms) has a core of cherry wood and in the centre there is a circular disk acting as connection for the four arms. The inverse is covered with