18th century, it was decided to build a structure that was separate, but still connected, to the main cathedral. It is constructed of tezontle (a reddish porous volcanic rock) and white stone in the shape of a Greek cross with its southern facade faces the Zócalo. It is connected to the main cathedral via the Chapel of San Isidro. The interiors of each wing have separate uses. In the west wing is the baptistry, in the north is the main altar, the main entrance and a notary area, separated by inside corner walls made of chiluca stone and tezontle. Chiluca, 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 Patiño Ixtolinque. It was inaugurated in 1829. The exterior of the Baroque styled tabernacle is almost entirely adorned with decorations, such as curiously shaped niche shelves, floating drapes and many cherubs. Carvings of fruits such as grapes and pomegranates have been created to in the shape of ritual offerings, symbolizing the Blood of Christ and the Church. Among the floral elements, roses, daisies, and various types of four-petalled flowers can be found, including the indigenous chalchihuite. The tabernacle has two main outside entrances; one to the south, facing the Zócalo and the other facing east toward Seminario Street. The southern façade is more richly decorated than the east façade. It has a theme of glorifying the Eucharist with images of the Apostles, Church Fathers, saints who founded religious orders, martyrs as well as scenes from the Bible. Zoomorphic reliefs can be found along with the anthropologic reliefs, including a rampaging lion, and the eagle from the coat of arms of Mexico. The east facade is less ambitious, but contains figures from the Old Testament as well as the images of John Nepomucene and Ignacio de Loyola. Construction dates for the phases of the tabernacle are also inscribed here. Interior Altars High Altar This disappeared in the 1940s. In 2000, a new altar table was made to replace the previous one. This was built in modernist style by the architect Ernesto Gómez Gallardo. Altar of Forgiveness The Altar of Forgiveness () is located at