Grosseto Cathedral (Cattedrale di Grosseto) is a Roman Catholic cathedral in Grosseto, Tuscany, Italy. It is the cathedral of the diocese of Grosseto and it is dedicated to Saint Lawrence.
It and was begun at the end of the 13th century, by architect Sozzo Rustichini of Siena. Erected over the earlier church of Santa Maria Assunta, it was only finished in the 15th century (mainly due to the continuing struggles against Siena).
The façade of alternate layers of white and black marble is Romanesque in style, but is almost entirely the result of 16th century and 1816–1855 restorations: it retains decorative parts of the originary buildings, including Evangelists' symbols. The layout consists of a Latin cross, with transept and apse. The interior has a nave with two aisles, separated by cruciform pilasters. The main artworks are a wondrously carved baptismal font from 1470–1474 and the Madonna delle Grazie by Matteo di Giovanni (1470).
The campanile (bell tower) was finished in 1402, and restored in 1911.