The region where the town of Mourão is inserted includes a great space and time diversity relating to the human presence. The present existing knowledge about the populations who lived and circulated in this space reveal that the area, be it the nearer (the shores) or the farer (town and parishes of Mourão) to the River Guadiana, knew a continuous occupation of human groups since pre-history till nowadays, being the river and its affluents motive and determinant factors to the existence of remains from the mentioned occupation. Thus, the river attracted to its shores essential or complementary activities to economical survival traditional cycle.
Since the prehistoric period the area presents several and abundant registries of the human presence. Places as Barca, Quinta da Fidalga and Agualta, the Mercador and the Porto das Carretas, among others, state that presence, visible in the lytic industries, in the ceramics remains, in the cave-art manifestation and in the megalithic monuments as well as the Dolmen of the old cellulose factory (Portucel).
The important Roman presence in the territory of Mourão is evident in the surroundings of the old Aldeia da Luz. The Castle of Lousa, a fortified building from the Roman period (1st century b. C.), was the more visible Roman heritage element in the municipality. Presently it is submersed but may be virtually visited through a CD-rom made by the EDIA, SA, which registers its memory.
Between this and the medieval period the human characterization of Mourão is uncertain. With its historical origins lost in time and surrounded by tradition, the primitive town of Mourão would have been placed, perhaps, in the so-called Vila Velha (Old Town). This was the object for archaeological digging before it was submersed by the waters of the River Guadiana, it was registered the existence of a necropolis associated to a church as well as the identification of a great dimension housing area
On the medieval period there are references to Mourão, but its rituality shows as an element integrated in the frontier vague stance between the several kingdoms resulting from the Christian Conquest, sometimes belonging to the Kings of Castela, sometimes under the domination of the Portuguese kingdom.
The prior of the Hospital Order, D. Gonçalo Egas, conceded to Mourão its first Foral in 1226 and D. Dinis confirmed it in the 27th of January, 1296. This king recognized , in the meeting of Salamanca (1298), D. Teresa Gil as owner of the place and Mourão became the property of the Portuguese crown after her death.
After the burial of D. Teresa Gil, the Portuguese king concedes to a Spanish nobleman, D. Raimundo de Cardona, the privilege of buying Mourão, fact which was consummated in 1313, when he made a high amount loan to a Jewish man. Due to his impossibility to honour the assumed compromises, Mourão was once more auctioned in 19 April, 1317, in the porch of the Church of S. Pedro do Tojal, being this time acquired by a merchant of Monsaraz called Martim Silvestre , by 11 000 pounds. However, due to the social incompatibilities between the merchant and the king, the latter will demand its devolution by the same selling price, and will make a new concession to D. Raimundo and to his son Guilherme de Cardona.
As to the crisis of 1383 – 1385, Mourão joined the Master of Avis’s cause as it is referred in the chronics of Fernão Lopes, and was attacked by devastating incursions from Castela.
Regarding the alcayde position in Mourão, this was attributed by the future king D. João II to Diogo de Mendonça remaining in this family until the kingdom of D. Afonso VI. When the dualist monarchy was established (1580), Mourão, to its main-alcayde Francisdo de Mendonça, joined the Spanish cause. After 60 years, the town passed to the conspirators’ side in the person of Pedro de Mendonça Furtado. The heir of the alcayde position of Mourão, a close friend of the Duke of Bragança, felt the need to dignify his family’s image being one of the first conjured to take part in the events which led to the 1st of December in 1640.
After the Restoration in the ambit of the Independence Wars, Mourão suffered the impact of the frequent frontier riots being assaulted by the enemy army in several occasions. To highlight the siege by the Duke of S. German during which, under Captain João Fereira da Cunha’s command, Mourão resisted only for six days revealing that way the fragility of the wall of the castle. Once that, the conquest of Mourão became a frontier priority, the regent queen, D. Luísa de Gusmão, deeply engaged herself to take the town from the Spanish, which occurred in the 29th of October, 1657. In that conquest, Joane Mendes de Vasconcelos had a determinant role.
In the 18th century, Mourão suffered the effects of the earthquake of 1755, which, together with the repair, enlargement and consolidation works of the defensive structure of the castle, started in the 17th century, and the destructed condition left by the enemies led to the redrawing of the urban trace of the town.
In the 19th century, the new administrative reform led to the creation of the municipality limits, which in the case of Mourão contributed to its extinction and annexation to the Municipality of Reguengos de Monsaraz by the Law decree of the 24th of October, 1853. In 1861, the Municipality of Mourão was established again.
Mourão is presently surrounded by the water of Alqueva profiling itself to this new natural resource as one of the engines to the sustainable economical development of this place and Municipality.