On the hill overlooking the center of Lisbon are the walled remains of a Moorish castle; Castle St. Jorge. Archeological excavations have revealed the existence of human habitation in the valley of the Tagus River as far back as the sixth century B.C. The first fortifications on the hill date to the second century B.C. During the tenth century A.D., these fortifications were rebuilt by the Moors. By 1147, Alfonso Henriques had freed Lisbon from the Moorish rule. One hundred and eight years later (1255), Lisbon became the capital of Portugal and the castle became the fortified residence of Alfonso III ( who was the first to use the title "king of Portugal"). Between 1373 and 1375 the compound was enclosed by a 17,700 foot long wall, which included 77 towers. By the end of the 14th century, the castle was dedicated to St. George. When Portugal became part of the Spanish empire in 1580, the castle became an important military post. The Portugese Restoration War (1640 to 1668) brought independence back to Portugal. An earthquake in 1755 severely damaged the castle and contributed to its eventual decay. While the trip to castle is quite a climb up the hill (although there is a trolley that goes up to near the entrance), there are several important museums and churches along the way (which are well worth visiting in their own right). One cautionary note; locals informed us that because of the tourist nature of everything on the hill, pickpockets are prevalent. So beware of your surroundings and safeguard your valuables.