According to Aztec mythology, Xelhua was one of the seven giants who ascended the mountain of Tlaloc to escape the flood, and built the Great Pyramid of Cholula. The pyramid was dedicated to the god Quetzlcoatl. It is the largest pyramid in the world. There were an estimated 100,000 people living there at it’s height. There is an advanced system of tunnels in place within the pyramid.
It currently resembles a hill with a church on top. It is a major Catholic pilgrimage destination. The whole pyramid has not been excavated and restored. It contains six superimposed structures, which were used for each ethnic group.
The first study on the pyramid was performed in 1881, with exploration beginning in 1931. Murals, structures, and patios have been found, as well as many altars.
It is considered archaeologically important and is well protected.
The above information and photos were found at Wikipedia.