Olivenza (oliˈβenθa) or Olivença (oliˈvẽsɐ) is a town in southwestern Spain, close to the Portugal–Spain border. It is a municipality belonging to the province of Badajoz, and to the wider autonomous community of Extremadura.
The town of Olivença was under Portuguese sovereignty continuously between 1297 (Treaty of Alcañices) and 1801, when it was occupied by Spain during the War of the Oranges and ceded that year under the Treaty of Badajoz. Spain has since administered the territory (now split into two municipalities, Olivenza and also Táliga), whereas Portugal invokes the self-revocation of the Treaty of Badajoz, plus the Treaty of Vienna of 1815, to claim the return of the territory. In spite of the territorial dispute between Portugal and Spain, the issue has not been a sensitive matter in the relations between these two countries.
Olivenza and other neighbouring Spanish (La Codosera, Alburquerque and Badajoz) and Portuguese (Arronches, Campo Maior, Estremoz, Portalegre and Elvas) towns reached an agreement in 2008 to create a euroregion.
Olivenza is located on the left (east) bank of the Guadiana river, at an equal distance of south of Elvas in Portugal and Badajoz in Spain. The territory is triangular, with a smaller side resting on the Guadiana and the opposite vertex entering south-east and surrounded by Spanish territory. Besides the city, the municipality of Olivenza also includes other minor villages: San Francisco (São Francisco), San Rafael (São Rafael), Villarreal (Vila Real), Santo Domingo de Guzman (São Domingos de Gusmão), San Benito de la Contienda (São Bento da Contenda), and San Jorge de Alor (São Jorge da Lor).
The catchment area which drains Olivenza consists of irregular water streams regularly drying up in the Summer. The Olivenza river—whose water is dammed up in the reservoir of Piedra Aguda, opened in 1956 and with a capacity of 16.3 hm3—discharges into the Guadiana, leaving the city to its west and, then, south.