At canal level you get a much better view of the last operating canalside wharf in Birmingham; now converted into apartments, the building used to be a warehouse for canal goods. The area where you are stood in was once the hustling centre of industry in Birmingham (the city of 1000 trades); papermills, bed factories and many more businesses all manufactured goods here for selling the world over.
This cache is hidden at the point where only those with a magic key can go, not us lowly muggles