Probably the closest thing there is to seeing a unicorn.
There aren't exactly a whole lot of Bugatti Veyrons out there. Seeing one is rare enough for most people, but seeing five in one place at one time is very rare indeed. On top of that, each of them is noticeably different from the others. To start, there's the "regular" 16.4, then a Grand Sport, a Super Sport, a Mansory Vivre and finally one one-off special edition, the Pur Blanc Super Sport, sometimes called the "Panda."
Not only is it impressive to look at, just consider for a moment what the collected cost of these cars must have been.