Mexican archaeologists have discovered 45 skulls and over 200 jawbones as well as a sacred Aztec tree trunk at the ruins of a ceremonial site in the throbbing heart of Mexico City's historic center.

The remains were discovered near the ruins of the Templo Mayor, one of the largest and most important temples of the Aztec capital of Tenochtitlan, which was used for religious ceremonies and human sacrifices.

Archaeologists said that researchers planned to finish cleaning the remains before conducting further analysis to determine who they were and how they died.

Unlike most other similar discoveries, the skulls were not found alongside offerings of ceramics, jewelry or animal bones.

Archaeologists believe that the remains likely date from the second stage of the Templo Mayor's construction, between 1375 and 1427.

The site also found a sacred tree, planted in a circular stone structure.

Archaeologists said that trees held important religious significance in Aztec culture.

In August, another sacred tree trunk was found alongside 1,700 bones another location near the Templo Mayor.

The Aztecs, a warlike and deeply religious people who built monumental works, ruled an empire stretching from the Gulf of Mexico to the Pacific Ocean, encompassing much of modern-day central Mexico.

Their often bloody reign began in the 14th century and ended when they were subjugated in 1521 by the Spanish led by Hernan Cortes.

The Templo Mayor was destroyed when the Spanish razed the Tenochtitlan after the Aztecs surrendered on August 13, 1521.