MEXICO CITY (AP) — Recent discoveries at Mexico's Teotihuacan ruin site suggest that water features may have been a key part of the complex.

The water connection would be an odd twist for Teotihuacan, a 2,000-year-old complex in an arid valley north of Mexico City.

Archaeologists reported last week they have largely excavated a 340-foot (103-meter) tunnel under the Temple of the Plumed Serpent.

Archaeologist Sergio Gomez said Wednesday that water marks on the wall indicate the chambers and offerings at the end of the tunnel were under water.

Gomez said the plaza outside the temple also probably had been flooded with water and used as a reflecting pool. Researchers found that drains around the Ciudadela plaza had been ritually blocked with material that included the decapitated, mutilated remains of 50 human sacrifice victims.