Map - Oeiras Municipality, Portugal (Oeiras)

Oeiras is a town and municipality in the western part of Lisbon metropolitan area, located within the Portuguese Riviera, in continental Portugal. The municipality is part of the urban agglomeration of Lisbon and the town of Oeiras is about 16 km from Lisbon downtown. The population in 2011 was 172,120 living in an area of 45.88 km2, making the municipality the fifth-most densely populated in Portugal.

Oeiras is an important economic hub, being one of the most highly developed municipalities of Portugal and Europe. It has the highest GDP per capita in the country, being also the second highest-ranking municipality (immediately after Lisbon) in terms of purchasing power as well as the second highest-ranking in the country as far as tax collection is concerned. These economic indicators also reflect the education level of its inhabitants, as Oeiras is the municipality with the highest concentration of population by tertiary education attainment in the country, their entrepreneurial prowess and the economically liberal mindset of Oeiras' society in general. It also has the lowest unemployment rate in the Lisbon area.

The mild climate, access to water, quality of its soils and geographically advantageous location at the mouth of the Tagus River attracted early settlement to this region. The rugged hilltops of the interior conditioned cultivation and allowed the settlement of several small agricultural castros within the region's limits, such as Castro of Leceia (which was classified in 1963 as a property of public interest). This archaeological site is a witness to the early settlements and defensive structures that developed during the Chalcolithic period, although Paleolithic camps such as Gruta da Ponte da Laje are indicative of earlier settlements.

Remnants of the Roman occupation of the Iberian peninsula are evident in many places throughout the municipality, including mosaics, specifically along the Rua das Alcássimas, and a Roman bridge. The later Arab conquest left behind several toponymic markers, including Arab/Moorish place names such as Alcássimas, Algés, Alpendroado and Quinta da Moura.