Monteggio is a former municipality in the district of Lugano in the canton of Ticino in Switzerland . On 18 April 2021 the municipalities of Croglio , Monteggio, Ponte Tresa and Sessa merged to form Tresa.

Monteggio is first mentioned in 1466 as da Montegio. Until 1819 the current village core was called Albio. The name comes from the fortified seat of the Capitanei of Sessa, the ruins of which are on the site of the Chapel of S. Adalberto (first mentioned in 1428) located in Castello. During the Middle Ages the history of Monteggio was closely connected to the Sessa family.