A team of underwater archaeologists, including National Geographic Explorer Kathleen Martínez and National Geographic Explorer-at-Large Bob Ballard, uncovered rows of towering structures that may have been columns, reaching over 20 feet (6 meters) high, within the Mediterranean Sea. The researchers also found evidence of polished stone floors, cemented blocks, ship anchors and tall storage jars called amphorae — all dated to the time of Cleopatra.