 The interiors of each wing have separate uses . In the west wing is the <unk> , in the north is the main altar , the main entrance and a <unk> area , separated by inside corner walls made of <unk> stone and tezontle . <unk> , a white stone , covers the walls and floors and the tezontle frames the doors and windows . At the crossing of the structure is an octagonal dome framed by arches that form curved triangles where they meet at the top of the dome . The principal altar is in the ornate Churrigueresque style and crafted by indigenous artist Pedro <unk> <unk> . It was inaugurated in 1829 . 
