My wife and I had previously been to Naples three times, but had never before been to the Duomo. That was our loss. First, there is no charge to enter the Duomo. If we’re ever lucky enough to get back to Naples, we’ll be sure to allow at least half a day for the Duomo. It’s gigantic, it’s truly magnificent, and it’s a very complex structure. The Duomo has total of ten side chapels (five on each side). A large chapel inside the Duomo on the right side, known as the Chapel of St. Januarius (San Gennaro), displays gorgeous artwork in every medium you can think of. But that Chapel is just a tease for the exhibits displayed in the spectacular Museum of the Treasures of San Gennaro (Museo del Tesero di San Gennaro), the entrance to which is located outside and just to the right of the Duomo. There is a 10€ fee to enter the museum. A large chapel inside the Duomo on the left side is the Basilica of Santa Restituta, the oldest basilica in Naples, which holds the Baptistery of San Giovanni in Fonte, the oldest surviving baptistery from medieval Europe. There is no fee to enter the Basilica, but there is a 2€ fee to enter the Baptistery of San Giovanni in Fonte. Formerly accessible from the Basilica of Santa Restituta is a subterranean archaeological zone, which includes catacombs and remains of Greek and Roman buildings and roads (the archaeological zone is now closed indefinitely.) The spectacular Museum of the Treasures of San Gennaro (Museo del Tesero di San Gennaro) is located in just to the right of the Duomo. Be sure to GO TO THE MUSEUM; it’s worth it.

The cathedral of Santa maria Assunta has an elegant facade; the rest of the exterior is covered with neighboring buildings, but not much is missed. The imposing interior deserves a close look to all the chapels. Two side chapels are specially spectacular, the one in the right nave devoted to San Gennaro and the one in the left nave, the old Santa Restituta byzantine Basillica. You can admire both free of charge ( San Gennaro will need some time, with all its baroque ornaments) but also both sell tickets to special exhibitions very worthy. San Gennaro holds the cathedral’s treasure (among them, a mitre that rivals a king’s crown) and Restituta has a Saint John protochristian baptistery, with remains of the original mosaics.

Nice church and worth a visit. Naples is a city full of nooks and crannies that you discover by walking and this church is tucked away in this city. Worth a trip. Wear "decent clothes" as there are guards who prevent you from entering if you are wearing short skirts, showing your shoulders, shorts etc. I am not kidding, If you bring a shawl or something to cover yourself they allow you in.

I've got to be honest, this isn't the most amazing cathedral you'll ever visit but it's worth visiting and having a wander around. Probably spent about 15mins inside. There is a museum inside that you have to pay for but we didn't do that. It wasn't that crowded so it was nice to spend some time in stillness before venturing out into crazy Naples again.

This beautiful cathedral houses the remains of the great patron saint of Naples, San Gennaro. This relics are viewable in a crypt under the altar. Many of the side altars are beautifully rendered with typical Neapolitan touches. The building is just north of the Spaccanapoli and easy to find.