Uxmal is a spectacular Mayan site and is located about three hours from Taninah. Uxmal (pronounced OOSH-mal -- "thrice built" in the Mayan language) started to flourish in the 7th century AD (though many changes were made over the following 300 years.)
Be sure to visit the Pyramid of the Magician (according to Maya legend, it was built overnight,) the Nunnery quadrangle, the House of Turtles, and the Governor's Palace.
The Uxmal Mayan Ruins are 60 miles south of Merida