This decommissioned relocation site for UK government could provide inspiration for fiction, or potential survivor site following the event known as Yellow Dawn.
Conceived in 1956 as the British government’s alternative seat of power in the event of a nuclear strike, it was completed in 1961 and decommissioned 30 years later. It had various aliases: Hawthorn Central Government War Headquarters, Stockwell, Subterfuge, Turnstile, and Site 3. Situated between 20 to 33 metres below ground, it is 1,000 metres long by 200 metres wide, and has 16 kilometres of roadways. A fleet of battery-powered buggies navigated the vast grid of tunnels. If fully occupied it was designed to house 4000 government ministers and civil servants including the Prime Minister, Cabinet Office, local and national government agencies, intelligence and security advisors and domestic support staff. Fully fitted with an infirmary, bakery, laundry, two large kitchens and serving areas, telephone exchange, store rooms, office space, living accommodation, maintenance areas and workshops and an area for the storage and charging of the bunker’s electric buggies.
Very reminiscent of something you might find in the roleplaying game The Morrow Project: http://en.wikipedia.org/wiki/The_Morrow_Project – which had a massive influence on my young imagination in the early 1980s, followed by Gamma World http://en.wikipedia.org/wiki/Gamma_World.
You can dig into more detail about the bunker here: http://www.burlingtonbunker.co.uk but I’ve included some images for immediate visual inspiration. It would certainly make a great location for a piece of fiction, or as a base for survivors of Yellow Dawn. Of course it would be a terrible location to be if the Infected somehow got within the perimeter, particularly with the Influence of Hastur warping the reality of any unfortunate souls who succumb with the sanity shredding impact of this malign Great Old One.