The ‘secret’ runway for the former East German party cadre’s hideout at Wandlitz (to the NE of Berlin) was in a bend in the road. It’s now part of the B273 road, from Oranienburg to Bernau. The runway was ment to be used by small transports like the An-2, An-14 and L410. Unfortunately i don’t know of any flying from that stretch of concrete.