A yearslong exploration of a tunnel sealed almost 2,000 years ago at the ancient city of Teotihuacan yielded thousands of relics and the discovery of three chambers that could hold more important finds, Mexican archaeologists said Wednesday.

Project leader Sergio Gomez said researchers recently reached the end of the 340-foot (103-meter) tunnel after meticulously working their way down its length, collecting relics from seeds to pottery to animal bones.