Today you can choose to visit the Maya ruins of Uxmal, a 1-hour drive from Merida, on an optional tour which includes transport and a local guide. It's thought that the city was constructed around AD700, was home to around 25,000 people and once dominated the region along with Chichen Itza. Much of the site is decorated with masks of Chac, the rain god, and important buildings include the Pyramid of the Soothsayer, the Quadrangle of the Nuns, the Governor's Palace, the House of the Tortoises and the Ball Court. Alternatively, you could choose to take an optional guided tour to the Celestun Bird Sanctuary, home to large flocks of flamingos as well as numerous other migratory birds.