The patroness of Magreglio is Saint Martha (Santa Marta), celebrated on 29 July; the municipality holds the Chiesa Santa Marta.
The village houses the Museo del ciclismo del Ghisallo (cycling museum) and the Santuario della Madonna del Ghisallo; in the old town stand the 16th-century monastery, now Ca' Mojana, and the Ca' del Tay with its characteristic «lobbie» (loggias). The municipality also holds the Menaresta, the source of the river Lambro.
