Ancient staircase in sinkhole (IMAGE) Brigham Young University Caption Researcher Chris Balzotti climbs an ancient staircase discovered in a sinkhole near Coba, Mexico. Credit Richard Terry Usage Restrictions None License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.