The patron saint of Lastra a Signa is Saint Martin of Tours, celebrated on 11 November in the church of San Martino a Carcheri.
In the post-war years, the funfair rides for the Mid-August Fair (Fiera di Mezzagosto) were set up in the town square; in the 1990s the square was used as a car park, until in 2000 the town council proposed its redevelopment through a public competition. The town also holds the church of Santo Stefano a Calcinaia and that of Santa Maria a Castagnolo.