Anti-aircraft defence was 19 "sugar-loaf" type flak towers.
The telephone/telex bunker "Amt 500" covered 4881 sq.m on two levels. Walls were up to 3.2 metres thick, ceiling was 3 metres thick concrete with an outer 1-metre thick shell above it.
MAYBACH I consisted of twelve concrete structures disguised as residential houses, each 36.2 m x 16.39 m. There were two levels of fortified underground cellar, a single ground level floor and another level in the roof, all sub-divided into rooms. The houses were hermetically sealed against gas attack. Water was supplied from underground springs. All buildings were connected by an underground gallery. Maybach I was occupied by the Army General Staff on 26.8.1939 and it was from Zossen that the orders were issued, and retracted, for the attack on Poland scheduled for that day. The OKW command centre was transferred to Zossen from Berlin on 29.3.1943.
MAYBACH II was completed during the war as a Fuehrer-HQ: it consisted of 23 more buildings similar to those at MAYBACH I, seven of which were allocated for Hitler and his entourage. Hitler never occupied MAYBACH II mainly because he felt uncomfortable at being surrounded by Army personnel. The other buildings were occupied by Army Transport. Other branches joined later in the evacuation process from Berlin.
In the major US air raid on 15 March 1945, 675 heavy bombers inflicted damage amounting to the destruction of several wooden barrack huts and putting the main telephone cable out of use for two hours.
Zossen was evacuated before the Russian advance on 20 April 1945 and fell more or less intact into Soviet hands. Once the state-of-the-art telephone equipment had been carted off, the entire site was reported destroyed by explosives. However it later served as the HQ for Soviet Forces in Germany (GSTD), and passed to the Federal Republic in 1994.
Source: Seidel and Zeigert: The Fuehrer-HQs, Greenhill Books 2004. There is more information contained in this book relating mainly to the telephone/telex side.