The Citadel is one of the most important sites in the capital of Jordan; Amman. It dates back to the Bronze Age and consists of ruins from the Roman and Umayyad eras in addition to other eras. It is located on a hill in the center of Amman, so you can view the rest of the city from there.
Ajlun Castle (Qal'at Ajloun) was built by one of Saladin's generals in 1184 AD to control the iron mines of Ajlun, and to deter the Franks from invading Ajlun.
Umm Qais, is a town in Jordan located near Irbid in the north. The city used to be known as Gadara in ancient Greek. It has Hellenistic-Roman ruins and has a very beautiful view on the Lake Tiberias (Sea of Galilee) in north of Palestine.
Jerash, or the city of 1000 columns, is an Roman ancient city that resides in the north of Jordan.