If you planning to vacation in the Riviera Maya, you may want to take a couple days and head over to the State of Yucatan. Izamal is a quaint colonial town with a history of the the Maya in Pre-Columbian Times with five ruins sites in the area. After the Spanish Inquisition, a monastery was build on top of the acropolis. This monastery is the largest religious development second only to the Vatican.
Renting a bike is one of the easiest ways to get around. There are two great routes people generally take, one is a little longer than the other and you can see not only the churches and Mayan ruins in the area, but visit some local artisan workshops.