Grosseto Cathedral is a Roman Catholic cathedral dedicated to Saint Lawrence. Construction began at the end of the 13th century, under the architect Sozzo Rustichini of Siena. Erected over the earlier church of Santa Maria Assunta, it was not finished until the 15th century (mainly because of 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 restorations in the 16th century and in 1816–1855; it retains decorative parts of the original buildings, including the symbols of the Evangelists. The groundplan is a Latin cross, with transept and apse.