As part of an advertising campaign for Hot Wheels, a construction crew in Bogotá, Colombia, installed a facade for a loop. From the side, it resembles the loop tracks that Mattel has sold for years. You'll have to, sadly, wait a little bit longer before experiencing a real one.
Link (Google Translate) via Not Cot
It's been done. :D
http://www.youtube.com/watch?v=H90cqD817SQ
Which reminds me of the "The Bridge to Nowhere".
http://acidcow.com/pics/18348-storseisundetvthe-bridge-to-nowhere-6-pics.html
4 out of 5 Druglord kids prefer HotWheels.