The name of the town is spelled Tui in both Galician and Portuguese, and Tuy in Spanish.
After the campaigns of Alfonso I of Asturias (739-757) against the Moors, the town lay abandoned in the largely empty buffer zone between Moors and Christians known at the time as "The Desert of the Duero" and was part of the "Repoblación" (repopulation) effort carried out a century later, during the reign of Ordoño I of Asturias (850-866).
Today the town centre is near the Inn of San Telmo. On the top of the hill, the cathedral (XI-XIII century) preserves the Romanic period in its main vestibule, and the Gothic period in the western vestibule.
Two bridges connect Tui and Valença: Tui International Bridge (known in Portugal as Valença International Bridge), completed in 1878 under the direction of Gustave Eiffel, and a modern one from the 1990s. Both countries being signatories of the Schengen Treaty, there are normally no formalities in crossing what is the busiest border-point in Northern Portugal.
On October 24, 1925, Lúcia Santos (one of 3 Portuguese children witnesses of the apparition is now popularly known as Our Lady of Fatima) entered the Institute of the Sisters of St. Dorothy as a postulant in the convent in Tuy.
The town has two museums, one dedicated to archaeology and sacred art, and the other is the diocesan museum.
Tui has 11 districts: Malvas, Pexegueiro, Areas, Pazos de Reis, Rebordans, Ribadelouro, Guillarei, Paramos, Baldrans and Caldelas.