Viareggio remained under the control of the Austrians until 1817 when , as part of the agreements from Congress of Vienna , Maria Luisa di Borbone was assigned the new Duchy of Lucca .
Viareggio remained under the control of the Austrians until 1817 when , as part of the agreements from Congress of Vienna , Mary Louia of Spain was assigned the new Duchy of Lucca .