At the end of Via San Gregorio Armeno, near the corner of Via Tribunali is the Church of San Lorenzo Maggiore. Excavations under the church reveal parts of the Roman city, including what was the Roman Forum. Several scenes, such as the oven in the photo, have been set up to represent the way it probably looked in Roman times. Your ticket to the excavations (scavi) also includes the Museum of San Lorenzo Maggiore with works from the Greek and Roman period through the 19th century and the Capitolare and Sisto V rooms with beautifully frescoed ceilings.
On Via Tribunali there's an entrance to Naples Underground, a tour that takes you through the ancient aqueducts now buried under the modern city and there are also excavations under the Church of San Paolo Maggiore.
Lunch Stop - Recommended Restaurants: From Via San Gregorio Armeno, turn left onto Via Tribunali. Trattoria Enoteca Campagnola serves typical inexpensive Neapolitan food, Via Tribunali 47 (closed Tuesday). For pizza try one of the Sorbillo pizza spots. See Where to Eat in Naples Historic Center.