St Martins Cathedral, Lucca. Lucca is a city and comune in Tuscany, the north-west of Italy, situated on the river Serchio in a fertile plain near the Tyrrhenian Sea. It is the capital city of the Province of Lucca. Among other reasons, it is famous for its intact Renaissance-era city walls. Frediano, an Irish monk, was bishop of Lucca in the early 6th century. At one point, Lucca was plundered by Odoacer, the first Germanic King of Italy.