The 2,300-year-old Mayan pyramid at Noh Mul was destroyed to make fill for roads in Belize, local media report.
The limestone from which the pyramid is made is prized by local contractors for building and repairing.
The pyramid was overgrown with trees and shrubs, but archeologist John Morris said there was no mistaking the structure. The willful destruction of ancient sites or monuments carries a penalty of 10 years in prison or a $10,000 fine.
Archeologists in the area are outraged and hope to salvage artifacts from the rubble.
The pyramid, which stood 65 feet tall, was built around 250 B.C. with hand-cut limestone bricks. The pyramid probably contained living quarters as well as tombs for local residents.