The largest was at Helmstedt-Marienborn on the Hanover–Berlin autobahn (A 2), through which 34.6 million travellers passed between 1985–89.[107] Codenamed Checkpoint Alpha, this was the first of three Allied checkpoints on the road to Berlin.[108] The others were Checkpoint Bravo, where the autobahn crossed from East Germany into West Berlin, and most famous of all, Checkpoint Charlie, the only place where non-Germans could cross from West to East Berlin.[109]