Turtles held special significance in Mayan mythology.

In the Mayan Myth of Creation, the paddler gods transported the Maize gods in a huge canoe that corresponded to the Milky Way until they arrived at the place of creation that we know as the belt of the constellation Orion. The Maya saw Orion's belt as a huge cosmic turtle. The god Chak cracked open the back of the cosmic turtle with a lightning stone. Watered and nurtured by the Hero Twins, the Maize Gods grew from the crack in the back of the turtle, which is now represented by the Ballcourt all across the Yucatan.

This structure is a representation and hommage to the great cosmic turtle.

http://www.isourcecom.com/maya/cities/uxmal/houseoftheturtles.htm