Harold Lloyd's Safety Last
Still amazing to watch almost a century later!
Its a great sequence, but contrary to popular belief it wasnt all done for real by Lloyd.
The beginning of the following clip shows how the clock tower sequence was done.
It has also been stated that Lloyd only did the first part of the climb up the building, the higher parts of the climb which are seen from a high angle and were done for real were performed by an unnamed stuntman who specialised in high climbs.