Hey quantum-x, here's something I came across recently... a 200+ hectare explosives depot which is now being nudged by suburban sprawl. In fact, the base has been abandoned and the land is now owned by a residential developer, although the portion that most of the ~15 buildings sit on has to be donated to Melbourne Water. I presume they'll be demolished eventually as they currently pose a safety hazard due to the asbestos used in the walls.
It's been off limits to the public for 60+ years and once MW takes possession it will stay off limits.
These are the "Y" labs which are distantly visible from public parkland in the Greenvale Reservoir. Apart from that point you wouldn't know the base is there.
Strange symbols to write on the walls of a warehouse which stores devices designed to explode and kill humans...
There isn't really anything breathtaking like huge machinery, but if you hunt around you can find interesting things. One of the warehouse entry doors has written on it:
<swastika logo>
HIEL HITLER
12/2/42
I AM A GERMAN SPY AGENT
NO 10015679