Genoa's cathedral was built circa 1098 in an area where archaeological excavations have revealed pre-existing Roman structures and the signs of an early basilica dating to the 5th or 6th century. Expanded over the centuries, the solemn, exquisite Cathedral of San Lorenzo preserves the ashes of St. John the Baptist, the patron saint of the city, which arrived in Genoa at the end of the First Crusade.
Beginning in the 9th century, San Lorenzo first supported then replaced the basilica of the Twelve Apostles as the city's cathedral, dedicated to San Siro, a bishop of Genoa, since the 6th century. San Siro was (and indeed is to this day) located outside the ancient heart of the city, towards the West.
The relocation of the cathedral gave a boost to urban development in the area, with city walls built in 1155 and Genoa's three ancient urban nuclei (the castrum, civitas and burgus) combining to become the heart of the city.
The consecration of the cathedral by Pope Gelasius II in 1118 marked the start of its reconstruction in Romanesque style; funds for the work arrived from the Crusades, other military ventures and city taxes.
Since 1133, the church has been the seat of the archbishop of Genoa. After the fire of 1296, the building was partly renovated and partly rebuilt: between 1307 and 1312 the façade was completed, the interior colonnades were rebuilt with capitals and false matronea, while preserving the Romanesque elements that were still in good condition, and the counter-façade was decorated with frescoes.
Several altars and chapels were erected between the 14th and 15th centuries; deserving of particular mention is the chapel designed to house the ashes of St. John the Baptist, a 15th century masterpiece in the left aisle. The small loggia on the north-east tower of the façade dates to 1455, and the one opposite, in the Mannerist style, to 1522.
In a city without squares and lacking a seat for secular power, the churchyard of San Lorenzo served as Genoa’s only public space throughout the Middle Ages, the stage upon which most of the city's political and civil life was played out.
In 1550, by order of the city magistrates, the architect Galeazzo Alessi from Perugia designed a reconstruction of the entire building, but only completed the roofing of the nave and aisles, the floor, the dome and the area of the apse. The work was completed in the 17th century, when the apse was decorated with the "Stories of San Lorenzo" by Lazzaro Tavarone, in a triumph of gilded stucco work.
Modified further over the course of the centuries, restoration work carried out between 1894 and 1900 gave the cathedral its current appearance, making the most of the medieval elements that distinguish it to this day.
Other splendid attractions are the Museo del Tesoro, accessed from within the cathedral, and the neighbouring Museo Diocesano.