The Old Frozen Bridge

Board

The old bridge is the only way ahead.

The gatehouse was designed with a puzzle in mind. Adventurers have to find a way into the gatehouse in order to cross. They can either climb through one of the broken windows or look for a place where the wall had been broken. 
Undenounced to them, a rather large werewolf has made this gatehouse his home. As soon as adventurers step onto the bridge platform, the werewolf will jump from the upper window (in a very cinematic way) and try to cut them off. The platform makes for a great boss fight arena.

NOTE: You can switch out the water for fog to make it more dramatic.

But please be creative and add your own ideas and adapt it to your own adventure as you wish.