Luxor is a city in Upper (southern) Egypt and the capital of Luxor Governorate. The population numbers 506,588 (2012 estimate), with an area of approximately 417 square kilometres (161 sq mi). As the site of the Ancient Egyptian city of Waset, known to the Greeks as Thebes, Luxor has frequently been characterized as the "world's greatest open-air museum", as the ruins of the temple complexes at Karnak and Luxor stand within the modern city. Immediately opposite, across the River Nile, lie the monuments, temples and tombs of the West Bank Necropolis, which includes the Valley of the Kings and Valley of the Queens. Thousands of tourists from all around the world arrive annually to visit these monuments, contributing greatly to the economy of the modern city. Luxor was the ancient city of Thebes, the great capital of (Upper) Egypt during the New Kingdom, and the glorious city of Amun, later to become the god Amun-Ra. The city was regarded in the Ancient Egyptian texts as ws.t (approximate pronunciation: "Waset"), which meant "city of the sceptre", and also as t ı͗pt (conventionally pronounced as "ta ipet" and meaning "the shrine") and then, in a later period, the Greeks called it Thebai and the Romans after them Thebae. Thebes was also known as "the city of the 100 gates", sometimes being called "southern Heliopolis" ('Iunu-shemaa' in Ancient Egyptian), to distinguish it from the city of Iunu or Heliopolis, the main place of worship for the god Ra in the north. It was also often referred to as niw.t, which simply means "city", and was one of only three cities in Egypt for which this noun was used (the other two were Memphis and Heliopolis); it was also called niw.t rst, "southern city", as the southernmost of them.