The hardest part about this cache will probably be the muggles. It is right in the middle of the CBD so retrieval and replacement will require the utmost stealth if trying during office hours. At other times it is far enough from the main crowds to be reasonably easy. If you know where it is of course!
The cache is a magnetic key holder, so please byo pen. It is in one of the obvious locations, but which one? Satellite signals will not be great here, so you will need to use all of the information given. The clue is slightly cryptic.