I've been to Chiusi before, but just stopping at the train station to change trains. It's main stopping point for trains heading to Rome. This past weekend I had a 90-minute gap between trains, and it was a beautiful day, so I decided on the spur of the moment to hike up to the historical center of Chiusi, which I'd never seen.
The station of Chiusi is frankly a bit boring, in the new part of town, in the flat river valley, so in contrast I was really pleasantly surprised to discover that the historic center is quite beautiful and unique, on a panoramic hill overlooking this hilly region on the border between Tuscany and Umbria.
90 minutes was just enough time for me to hike uphill, take a look around, and walk back to the station before missing my train, a great way to spend the afternoon! I hope I'll have a chance to stop in Chiusi again, since there's actually a lot to explore there, including the extensive National Museum of Etruscan Archeology.