Here's a link to the upcoming La Notte Bianca:
http://www.lanottebianca.it/
It's the third year they've done this - it's scheduled for Saturday night, September 17, 2005.
Everything stays open all night long and is mostly free and there are also special events planned...
I'm happy that I'll be able to check it out this year, usually my fall trip happens later in the year. Alot of times I never get in sinc with the time zone - so love the idea of nighttime museum visits - and the "free" part is also, obviously, great!