Kelvedon Hatch Bunker, Essex

The Bunker was built in the 1950’s originally as a hardened control centre for RAF Fighter Command, then used briefly as a civil defence centre, then as an emergency regional government site. By the 1990’s the Government decided that the threat of nuclear war had receded, and the mothballed bunker was sold back to the original landowners.
Today’s visitor enters through an anonymous bungalow (actually a guardhouse), and down a lengthy tunnel which leads to the lowest floor of the facility. There are many rooms on each of the three floors, most still containing age-stained equipment, and there are a number of small exhibitions and audio-visual film presentations. The exhibition explains how the up to 600 people inside were meant to rule the country in the event of a nuclear attack.
Your tour is self-guided by a personal handset, included in the admission price. A walk-through takes an hour, but if you stop to watch all the films and look at everything, a visit will occupy in excess of two hours.
I seemed to be the only person inside on the afternoon I visited, and after two hours I and a staff member who was walking through the complex to lock it up managed to scare each other somewhere in the depths of the bunker.
The route exits though a modern opening into a café and souvenir shop.