The Alentejo region is particularly rich in megalithic monuments, like the notable Anta Grande do Zambujeiro, located near Évora. Standing stones can be found isolated or forming circular arrays (stone circles or cromlechs). The Almendres Cromlech, also located near Évora, is the largest of the Iberian Peninsula, containing nearly 100 menhirs arranged in two elliptical arrays on an East-West orientation. Pre-historic fortified villages dating from the Chalcolithic are found along the Tagus river like that of Vila Nova de São Pedro, near Cartaxo, and the Castro of Zambujal, near Torres Vedras. These sites were occupied in the period around 2500–1700 BC and were surrounded by stone walls and towers, a sign of the conflictivity of the time. Starting around the 6th century BC, Northwest Portugal, as well as neighbouring Galicia in Spain, saw the development of the Celtic Castro culture ("cultura castreja"). This region was dotted with hillfort villages (called "citânias" or "cividades") that for the most part continued to exist under Roman domination, when the area became incorporated into the province of Gallaecia. Notable archaeological sites are the Citânia de Sanfins, near Paços de Ferreira, Citânia de Briteiros, near Guimarães, and the Cividade de Terroso, near Póvoa do Varzim. For defensive reasons, these hillforts were built over elevated terrain and were surrounded by rings of stone walls (Terroso had three wall rings). Houses were round in shape with walls made of stone without mortar, while the roofs were made of grass shoots. Baths were built in some of them, like in Briteiros and Sanfins. Architecture developed significantly in the 2nd century BC with the arrival of the Romans, who called the Iberian Peninsula Hispania. Conquered settlements and villages were often modernised following Roman models, with the building of a forum, streets, theatres, temples, baths, aqueducts and other public buildings. An efficient array of roads and bridges was built to link the cities and other settlements. Braga ("Bracara Augusta") was the capital of the Gallaecia province and still has vestiges of public baths, a public fountain (called Idol's Fountain) and a theatre. Évora boasts a well-preserved Roman temple, probably dedicated to the cult of Emperor Augustus.