Hi there, I have been interested to a worrying degree about this shopping centre since boyhood. My mum used to take us there at the weekend, although she preferred Maidstone and its higher quality retail emporia. Although I am now in my thirties I am still interested in the Pentagon and whenever I walk around the place I'm always hoping that a cleaner or security officer leaves some door open so I can take a peek down a hidden service corridor or somesuch.
There is a wealth of information available at the Civic Centre in Strood. I was surprised to learn that the Pentagon was supposed to be larger than present, and there were also plans to build 120 flats on top of the Brook car park, presumably the intention being that people would live in the flats, shop in the Pentagon and work in Mountbatten House(incidentally it took eleven years to fill that block).
A previous poster mentioned old signage. In the Brook car park on Level 2 there is an original orange logo sign that was there when I last visited a fortnight ago.
Apologies for the lengthy post but as I say, I do love the place, even though I shouldn't.