Scans on the pyramids of Giza, on the outskirts of Cairo, have found “several thermal anomalies,” which may be explained by “voids behind the surface,” according to Egypt’s Ministry of Antiquities. The investigation has found one “particularly impressive” anomaly at the Khufu pyramid — the only one of the Seven Wonders of the Ancient World still standing and the largest Pyramid ever built. The results have come just two weeks into Operation Scan Pyramids, which will last until the end of 2016. The scientific mission uses “noninvasive visualization techniques,” including 3-D scans with lasers and drones, to see inside the pyramids.