PIAZZA DEL NETTUNO
Very close to Piazza Maggiore, we find the Piazza del Nettuno, famous for its Fontana del Nettuno. This square was created by demolishing older, little edifices in 1564. Unfortunatly, when I went there, the fountain was closed for restoration.
Always on this fantastic square of Bologna, we can find the Sala della Borsa, that earlier was the headquartes of the municipality of Bologna. Under the ground floor, it is possible to see the ancient Roman ruins, that are visitable too. Since 1926 to circa 1950, it was used as a Stock Exchange. and then, it became a an indoor sports arena. Starting from 2001, it houses the principal library of Bologna.
BASILICA DI SANTO STEFANO
At 5 minutes walking by Piazza Maggiore, we find the Basilica di Santo Stefano, maybe the most charming holy complex of edifices in Bologna. It is built like the Santca Jerusalem, or rather the recreation of the holy places in Jerusalem.
This cathedral was founded by the saint patron of Bologna, Petronio, at the beginning of the V century A.C..
These are the monuments I saw in Bologna. I know, it's not a lot, but I reccomend you to catch the City RedBus, an hop-on hop-off tour of the city with a bus or even a little train.
I hope you'll like this "Bologna series", and here you can find the first part and the second one.