Three weeks in Northern Italy

I've only been two Italy twice, but a town I loved mostly for the atmosphere is Verona. It has a beautiful Roman colosseum (where operas and other performances are held), a great open-air market and a medieval museum. There's a lot of kitsch regarding Romeo and Juliet, but I reacted to it in stride, though I was an English literature major. (I think a lot of lit majors would have looked down on the tacky souvenirs and appeals to Shakespeare!)

Also, I'm told that a tour of the University of Bologna, the world's oldest, is worth it. In 1994, I was in the train station with my sister, and we wanted to tour the university, but we were on a tight schedule. Here's some background: https://www.unibo.it/en/university/who-we-are/our-history#:~:text=The%20origins%20of%20the%20University,of%20reference%20for%20European%20culture.

I can tell you that lodging for September this year is very, very costly on Lake Como, in Verona (opera festival) and in the Dolomites. Except at altitude, hot weather can be a big issue even into September, so consider your timing carefully.

Should you decide to spend a fair amount of time in Lombardy, and especially if you'll have a few days in Milan, check out the annual region-wide sightseeing card: https://abbonamentomusei.it/ As far as I can tell, foreign tourists can buy the card, though the lack of an obvious English (or other alternative-language option) on the website suggests Italians are the target market. The card certainly doesn't cover all the tourist sights in the area, but a lot of important ones are on the list:

Milan: Duomo, Pinacoteca di Brera, Pinacoteca Ambrosiana, ADI Design Museum (new), GAM (modern art), Galleria d'ItaliaCastello Sforzesco, Museo del Novecento, the Triennale and many others.

Lake Como: Villa Carlotta and villa Monastero.

There are lots of additional covered sights in other Lombardy towns, including Bergamo, and also some spots in the Aosta region. The card costs just 45 euros (or 35 euros for seniors). There's a similar card for Piemonte that looks equally good.

In northeastern Italy, I think Friuli-Venezia Giulia also has a regional sightseeing pass, but I haven't researched that one recently.

since you speak Italian, order a guidebook or two from a place like amazon.it since the destinations Italians go to can differ from those you'll find in English-language guidebooks

https://www.suedtirol.info/en/en

I primarily go to the Dolomites for skiing but hiking is also great. There is also a Suedtirol mobile App.

Here’s a trip report where I went to Bergamo, which I loved, along with Stresa, Cremona, Parma, Mantova and others.

https://community.ricksteves.com/travel-forum/trip-reports/trip-report-please-do-not-comment-until-i-change-the-title-filling-in-the-report-thanks

Check for any local festivals for the month you’re traveling.

The OP asked about Bologna and Bergamo, and those are both great choices. So is Verona—-the opera season ends September 7 with a performance of Carmen, and hotel prices should moderate after that.

Other places to consider would be Lago di Garda, Lago di Como, Parma, Modena, anywhere in the Dolomites (where German is as useful as Italian), and many others. It would help to know when you are thinking of visiting.