Amman's first municipal council was established in 1909. Amman witnessed rapid growth after its designation as Transjordan's capital in 1921, and after several successive waves of refugees: Palestinians in 1948 and 1967; Iraqis in 1990 and 2003; and Syrians since 2011. It was initially built on seven hills but now spans over 19 hills combining 22 areas, which are administered by the Greater Amman Municipality. Areas of Amman have gained their names from either the hills (Jabal) or the valleys (Wadi) they occupy, such as Jabal Lweibdeh and Wadi Abdoun. East Amman is predominantly filled with historic sites that frequently host cultural activities, while West Amman is more modern and serves as the economic center of the city.