Last summer I was disappointed when, 30 days in advance, I was unable to get on a tour of the US Mint in Denver. Due to security concerns, they now severely limit tours, and they were booked solid for more than 30 days. Over a decade before I showed up at the Mint and got the walk-through without any hassles at all.
Damned al-Qaeda. They're really ticking me off.
When I was 9, I got to go to Paris. When we went to the Louvre I didn't get to see the Mona Lisa; it was on tour in Moscow at the time.
In a couple weeks I'm headed to DC for a conference. I'm arriving a day early because I've never visited, and always wanted to visit, the Museum of American History. Turns out I won't be able to, because the museum is closed for renovations.