City of Bad Freienwalde (Oder); local district Wollenberg; Bunker Wollenberg (special military object 301): military truck of NVA (Nationale Volksarmee; National People`s Army) of GDR with radio equipment; Special object 301 of GDR army NVA was built in the Semmelberg mountain 150 m high as a bunker with two storeys. It opened in 1987 but operated only 3 months; in 1990. With special objects 302 and 303 of NVA; the Bunker Wallenberg should send radio signals in the troposphere in heights of 12 to 17 km; in case of atomic explosions.