One of the oldest cities in the world, Jerusalem was named as "Urusalima" on ancient Mesopotamian cuneiform tablets, probably meaning "City of Shalem" after a Canaanite deity, during the early Canaanite period (approximately 2400 BCE). During the Israelite period, significant construction activity in Jerusalem began in the 9th century BCE (Iron Age II), and in the 8th century the city developed into the religious and administrative center of the Kingdom of Judah. During its long history, Jerusalem has been destroyed at least twice, besieged 23 times, attacked 52 times, and captured and recaptured 44 times. The part of Jerusalem called the City of David was settled in the 4th millennium BCE. In 1538, walls were built around Jerusalem under Suleiman the Magnificent. Today those walls define the Old City, which has been traditionally divided into four quarters—known since the early 19th century as the Armenian, Christian, Jewish, and Muslim Quarters. The Old City became a World Heritage Site in 1981, and is on the List of World Heritage in Danger. Modern Jerusalem has grown far beyond the Old City's boundaries.