Piazza Bellini is super popular with university students and is the heart of Naples' nightlife scene. In the middle you'll see remains of the musa dating back to the 4th century. And the Conservatory and Museum of Fine Arts are located here as well.
From Piazza Bellini, you have a few options for which way to head next. On one side is Decumano Maggiore, the main street that will take you into the historic center. Or you can go Port'Alba which leads to Piazza Dante and Via Toledo.