The town is situated on a hill above the Arade River. Silves Castle (Castelo dos Mouros, Moorish Castle) is located on the top of the hill. It occupies ca. 12,000m². Archaeological excavations have shown that the oldest buildings date back to the 8th century, the stratigraphy is almost 6 m deep and contains Iron Age remains as well. The walls are made of red sandstone (gres de Silves) with a pisé-core and have been heavily restored in the 1940’s. Protruding towers of albarra-type protect the Northern slope. After the Christian conquest, the castle served as the seat of the alcaide-mor (provincial governor) till the middle of the 16th century, afterwards the towers were used as a prison.
The train station – an easy approach from Lagos or Faro – lies 2 km (1.25 miles) outside the town. There is a connecting bus, but it’s worth walking, allowing the town and its fortress to appear slowly as you emerge from the wooded hills. Under the Moors Silves was a place of grandeur and industry, described in contemporary accounts as being “of shining brightness” within its triple circuit of walls. In 1189 an army led by Sancho I put an end to this splendor, killing some 6000 Moors in the process. The castle is open to the public, its ghastly past lost amid well-tended jacaranda trees, oleander shrubs, and flowerbeds. The impressively complete sandstone walls of the Moorish fortress retain their towers and elaborate communication system, but the inside is disappointing: apart from the great vaulted water cisterns that still serve the town, there’s nothing left of the old citadel. Just below the fortress is Silves’ Cathedral, built on the site of the mosque in the thirteenth century. Much restored and rebuilt over the years, it contains the tombs of some of the Crusaders who died there. Flanked by two broad Gothic towers, it has a suitably defiant and military appearance, though the Great Earthquake of 1755 and centuries of impoverished restoration have left their mark inside.
Parts of the Almohad town wall, constructed from poured concrete, have been preserved, as well as the Almedina-gate. Other sights include the Santa Misericórdia Church with a fine door in Manueline style (the main body of the church was built in 1727-28); a museum for cork and the production of bottle corks in a defunct factory which is now also a center for cultural events called “Fabrica do Inglês” (The Englishman’s Factory); and the municipal museum (Museu Municipal de Arqueologia) with findings from the paleolithic onward.
Information provided by Wikipedia.