Sintra or Cintra (both: sēnˈtrə) [key], town (1991 pop. 20,750), Lisboa dist., W Portugal, in Estremadura. The region has orange groves and vineyards as well as marble quarries, but Cintra is known primarily for its beautiful mountain location. The view is superb, and Cintra has been rapturously described not only by Portuguese writers but also by Byron and other foreigners. It flourished as a Moorish city, and there are still ruins of a Moorish castle. With Lisbon it was permanently retaken from the Moors by Alfonso I in 1147 and thereafter was a favorite residence of the Portuguese monarchs. Cintra has a royal palace (15th–16th cent.) and an old convent surrounded by a lovely park. Near the town, in the Peninsular War, the Convention of Cintra was agreed upon (1808) by the French, British, and Portuguese.