Level 4 - The Royal Physician
Reach the top of Kaldwin's Bridge
Easy Method:
As part of the mission objectives you must disable the spotlights on the bridge to allow Samuels boat past, You will have to disconnect two Whale oil tanks. Right above these tanks are two chains connected to two giant wheel cogs, blink onto one of the chains and climb to the top. Once you jump off you the chain will only need to blink one or two platforms above you and the achievement will pop when you are standing on top of the bridge.
(These two chains also appear at the beginning of the bridge, look for the cogs)