Today,my first port of call was perhaps the most impressive building on the base, the massive building 299 the Avionics facility where electronic data from spy planes was down loaded. This bunker is the closest to being underground being semi sunken and partially mounded over with soil and grass . We entered through a very heavy blast door in a blast protected sunken open walkway. There are two such blast doors, one gives access directly to the main spine corridor but this is now wet so we used the other door which goes through the plant room. Again all the filtration and ventilation plant is intact and in good order. The bunker houses a number of vast rooms mostly rectangular but one 'L' shaped. All these rooms have been completely stripped apart from one small room which contains several electrical cabinets and what are presumably the control consoles for the bunker. Some of the walls have typical USAF wall art including an impressive painting of a raven.