Bairro Alto (Portuguese pronunciation: [ˈbajʁu ˈaltu]; literally: Upper District) is a central district of the city of Lisbon, the Portuguese capital. Unlike many of the civil parishes of Lisbon, this region can be commonly explained as a loose association of neighbourhoods, with no formal local political authority but social and historical significance to the urban community of Lisbon and of Portugal as a whole.

The bairro or "neighbourhood" resulted from urban expansion in the 16th century, forming outside the walls of the historical city, and is characterized by an almost orthogonal tract (developing from two phases of distinct urbanization).

It is a fundamental quarter of Lisbon, organized into a hierarchical scheme of roads and lanes: the roads, the structural axis, run perpendicular to the river; and the lanes, or secondary axis, cut parallel to the river. The matrix of allotments reflects the persistent use of the medieval layout; the division and multiplication of this module had its origin in the variations of the architectural typology. The space constructed is dominated by living spaces implanted in long narrow lots, three to four storeys in height, with asymmetric facades consisting of windows along the various storeys and staircases along the lateral flanks. Although less representative, the Pombaline-era buildings are common, essentially introducing modifications to the level of the façade's composition. Although there are many typological variations to the facade designs, certain elements are repeated, such as the corners, bay and sill windows, eaves and attics, securing a homogeneous urbanized front.

The Bairro Alto was born as a response to the social and economic transformation in Lisbon in the second half of the 15th century. Commercial development caused the growth in the population, and an associated expansion of construction within the medieval walled city. It was this phenomenon that resulted in the urbanization process of the Bairro Alto district, in two distinct phases.

The first phase began in 1487, after the death of Guedelha Palaçano, an influential figure in the kingdom: his widow transferred lands situated on the western limit of the city to the King's equerry, Filipe Gonçalves. The land rights for these lands were sold in 1498 to the nobleman Luís de Atouguia.

Between 1499 and 1502 various royal letters, signed by King Manuel, indicated that there was a need to demolish the balconies and verandas that occupied public spaces in the district. This was part of a package of legislative reforms issued to improve the image of the city. A similar royal charter in 1500, was issued with the objective of transforming the free lands that still existed with the old walls. These initiatives lead to the first urbanization, named Vila Nova do Olival (around 1502), situated around the old Convent of the Trinity, using a series of administrative tools and proceedings that would, later, be used in the creation of the Bairro Alto.

In 1505, the construction of the new royal palace, resulted in the move of the Court to the riverfront, and extended the city until the Cais do Sodré.

Around 1513, the first move to divide the lands of the Bairro Alto began, under the approval of Lopo Atouguia. Bartolomeu de Andrade and his wife Francisca Cordovil received permission to section-off plots for the construction of houses. The new urbanization would be designated Vila Nova de Andrade. After the establishment of a grid network of roads, the first houses began to be built, with the majority popping-up south of the Portas de Santa Catarina in 1514. The remainder of the homes also began occupying plots along Rua das Flores, Rua do Cabo, Rua do Castelo, the consecutively named Rua Primeira, Segunda and Terceira, in addition to the Rua da Barroca do Mar. By 1527, there were a total of 408 buildings in the area, totalling 1600 inhabitants.