Archaeologists have discovered an ancient mausoleum untouched by looters under a ruined citadel on Peru's northern coast, officials announced. The site, Chan Chan, was the capital of the Chimu kingdom that ruled much of Peru's coast before the Inca.

The tombs contained 38 bodies, and the scale of the mausoleum—nearly 55 feet on each side and 16 feet high—suggests the people buried there were Chimu elite. The tombs are about 600 years old, dating to just before or during the Inca conquest in the mid-1400s.

"This is the discovery of the decade," said Gabriel Prieto, a professor at the University of Florida. The team, led by archaeologist Jorge Meneses, slowly realized they had found something different as they removed debris. "In that moment we realized that the chamber had not been looted," Meneses said.

The excavation, near Trujillo, revealed a stairway descending eight feet into the mausoleum. One person was buried in the central chamber; the western room held artifacts and remains of about 20 people. Eighteen more were found elsewhere. Remains had ear ornaments, silver- or copper-plated necklaces, and jewelry of quartz, shells, and semiprecious stones. Metal weapons, heavy beads, and a wooden chest with colorful textiles depicting seabirds and monkeys were also found.

"It's really like a treasure chest," Prieto said.