The Canaa ruins at Caracol in southwestern Belize.

Located in what is today southwestern Belize, Caracol, Spanish for "snail," rivaled anything in Belize today. At its peak between A.D. 650 and 700, the city had a population estimated at 150,000 (Belize's entire population is only about 50,000 more than this today). Caracol's largest structure, the 138-foot Caana (Sky Place), is the tallest building in either ancient or modern Belize. All told, in its prime, the site covered almost 15 square miles, had more than 36,000 occupied buildings, and included over 22 miles of sacheoh, or "white roads," made of blocks topped with crushed stone and plastered. A tomb found beneath a bench in the front room of Structure A3, a temple rising 52 feet above the Main Plaza, contained a single skeleton with 18 pounds of obsidian and 88 pounds of chert.

Source: http://www.pbs.org/wgbh/nova/maya/worl_sans2_05.html