As civilization became more sophisticated, news of some of the great building achievements spread throughout the Ancient Greek Empire. Society had progressed to the point where man-made marvels were just as worthy of admiration as nature's wonders. What prompted the first list of Ancient Wonders is difficult for historians to pinpoint. As early as 250 BC the Greek engineer Philo of Byzantium is thought to have quantified and named humankind's most outstanding feats of construction. Travelers of the ancient world journeyed to view these great sights of the times, from the Hanging Gardens of Babylon and the Colossus of Rhodes to the Lighthouse at Alexandria to the Great Pyramids of Giza, the only Ancient Wonder still standing today, and still visited by thousands of tourists each year.