The FESTIVAL OF LIGHTS will take place again in 2014.
There's still some time left as it won't happen until October and it isn't exactly urbexing, but it's definitely worth a thought if you're interested in this sort of thing.
If you now wonder what the hell this is about, check out the website for full details: http://festival-of-lights.de
Save the date and mark your calendars!
P.S.: The location is just a suggestion for now