The Albert Clock is one of Belfast's most iconic landmarks.
It was constructed between 1865 and 1869, and stands 113 feet tall.
As the clock was built on wooden piles, on reclaimed land, the clock leans 4 feet to the perpendicular.
The cache is a magnetic nano hidden at the entrance to the clock itself.
Please be careful as there is a heavy footfall in this area due to nearby apartments and a nearby bus stop.