According to a frequently mentioned legend, described by Friar Amador Arrais in his 1589 work, Diálogos,[3] Portalegre was founded by Lísias in the 12th century BC, following the disappearance of his daughter Maia.

Lísias is desperate for his daughter's disappearance and goes in search of her, eventually finding her dead by a stream that today is named Ribeiro de Baco.

[5] The next king ordered the construction of the first walls in 1290, which he himself would surround for 5 months in 1299, following the civil war that opposed him to his brother, who asserted the throne claiming that Denis was an illegitimate child.

[citation needed] After Ferdinand I died in 1383 without leaving any male heirs, Leonor Teles assumed the regency of the Kingdom at the same time that she became acquainted with Count Andeiro, a Galician nobleman.

This position of the mayor provoked the revolt of the people of Portalegre, which surrounded the castle and forced Dom Pedro to flee to Crato.

The importance of the city at that time was reflected, for example, in the volume of revenue from the tax on Jewish quarters, which was similar to that of Porto, and only surpassed by those of Lisbon, Santarém and Setúbal.

The city is located at an altitude of between 400 and 600 m (1,300 and 2,000 ft), in the transition zone between the relatively flat landscape, but with many low hills to the south and west, and the mountainous system of Serra de São Mamede, which surrounds it to the north, east and southeast.

The unique characteristics of the landscape, flora and fauna are at the base of the creation of the Serra de São Mamede Natural Park, which includes a considerable part of the municipality's area.

Its position at the foot of Serra de São Mamede gives it cooler day temperatures, higher precipitation and lower insolation than the surrounding municipalities.

The municipality is composed of 7 parishes:[9] The house-museum of José Régio, a famous Portuguese poet, was installed in his home, in which he lived for 34 years.

[citation needed] In 1965, he sold his collection to the municipality of Portalegre with the condition of it buying his house, restore it and transform it into a museum.