Teggiano (Teggianese: Rianu), formerly Diano, is a town and comune (municipality) in the province of Salerno, Campania, Italy.

[3] Among the historic centers of the province, Teggiano is certainly one that has best preserved its ancient appearance of the fortress and it is this aspect which is shown to those who reach the old town.

The appearance of a Roman oppidum, still now remembered by the well preserved plan of the Cardo and of the Decumanus, was renewed in the Norman period and in the age of Frederick II of Hohenstaufen.

Teggiano became a fief of other noble families including the Gomez da Silva, the Grimaldi, the Caracciolo, the Villani, the Colonna, the Calà and Schipani.

The action of the Counter-Reformation and the presence of high offices brought in the later centuries a radical remaking of the Romano-Gothic churches in Baroque style.