According to tradition, the diocese of Braga dates back to the 3rd century, although historical confirmation dates back to 400. This makes it one of the oldest dioceses on the Iberian Peninsula. It is considered the center of the Christianization of Gallaecia, as the region in northwestern Spain and northern Portugal was called. When Rome's power was dismantled by invading Germanic tribes, Braga became the capital of the Kingdom of the Suebi from 409 to 584. Through the influence of Bishop Martin of Dumio, the Suebi converted to Catholicism around 550. Martin of Dumio had come to Gallaecia at this time and first founded a monastery in Dumio near Braga. He became Bishop of Dumio in 556 and finally Bishop of Braga in 562. However, the Suebi kingdom fell under Visigothic control and was incorporated into the Visigothic Empire in 585. Braga's importance subsequently declined. After the Moorish conquest of the Iberian Peninsula from 711 to 719, Braga lost its bishopric in 716. As a result of the Reconquista, the Christian reconquest, the Diocese of Braga was re-established around 1070. Bishop Dom Pedro, bishop of the diocese from 1071 to 1091 and the first archbishop, had a cathedral built, which was consecrated in 1089 by Bernard of Toledo. At that time, however, only the eastern chapels were finished. The present cathedral was built on the site of an older religious building, possibly an earlier cathedral. Despite the restoration of the Diocese of Braga, the city never managed to regain its former importance. Next to Toledo, which was declared the new metropolis by Urban II and was the residence of the Kingdom of Castile from 1087 and remained the capital of Spain until 1561, there was no room for Braga as a metropolis. Since Bishop Dom Pedro had himself awarded the pallium by Antipope Clement III in 1091, the former capital of Braga continued to decline in importance. Bishop Dom Pedro was deposed and banished to a monastery.
From 1093 onwards, the County of Portugal was ruled by Count Henry of Burgundy, who, together with Bishop Geraldo de Moissac, persuaded the Pope to reinstate Braga as an archbishopric in 1107. Construction work on the cathedral resumed and continued until the mid-13th century. The building, constructed in the 12th century, was designed in the Burgundian Romanesque style of the Abbey Church of Cluny and influenced the construction of many churches and monasteries in Portugal. The cathedral was frequently altered in the following centuries. Today, it features a mixture of different architectural styles, including Romanesque, Gothic, Baroque, and Manueline.
In 1905, Pope Pius X granted the cathedral the additional title of minor basilica.
Source: Wikipedia