MEXICO CITY (AP) — Mexican archaeologists said Monday they have unearthed the remains of an Aztec palace once inhabited by the emperor Montezuma in the heart of what is now downtown Mexico City.

During a routine renovation project on a Colonial-era building, experts uncovered pieces of a wall as well as a basalt floor believed to have been part of a dark room where Montezuma meditated, archaeology team leader Elsa Hernandez said.

Montezuma's palace complex — known as the Casas Nuevas, or New Houses to distinguish them from his predecessors' palaces — is thought to have comprised five interconnected buildings containing the emperor's office, chambers for children and several wives and even a zoo, according to Hernandez.

The Aztec constructions were razed by the Spanish, who built what is now Mexico City atop their ruins. Experts had long thought Montezuma's palace stood roughly on the site where the ruins were found, next door to the National Palace, Hernandez said.

The find is "another piece of a puzzle, (and) we hope to find several pieces," Hernandez said. Excavations are planned beneath several parts of the colonial building, which now houses the Museum of Culture, she said.

The basalt floor likely belongs to the Casa Denegrida, or the Black House, which Spanish conquerors described as a windowless room painted in black, Hernandez said. The emperor was believed to have reflected there on visions recounted by professional seers and shamans.

His reliance on such predictions may have contributed to his downfall, possibly prompting him to initially mistake Spanish conquerors for divine figures.

Montezuma was the Aztec emperor when Spanish conqueror Hernan Cortes marched into the Mexico Valley in 1519. He died after the Spaniards took him captive, and the city — and the Aztec empire — finally fell in 1521.