Tikal

The Temple of the Masks stands atop a remarkably preserved stepped pyramid at Tikal.

With its plethora of palaces, altars, shrines, and soaring temples, Tikal may be the premier Maya site. For over 1,100 years, the Maya built here, expanding the site until it covered an area of 25 square miles. In its heyday, the city may have had 100,000 residents, and it was ruled by a single dynasty of over 39 successive rulers. The heart of the site is the Great Plaza, which is surrounded by the Central Acropolis, the North Acropolis, and Temples I and II. In the North Acropolis alone, 100 buildings lie piled atop one another. Temple I is 145 feet tall, but it is dwarfed by Temple IV. At 212 feet, Temple IV, built around A.D. 741, is the tallest pre-Columbian structure in the Western Hemisphere.

Source: http://www.pbs.org/wgbh/nova/maya/worl_sans2_03.html