Jungholz  (Part of Austria only accessible from Germany.)

The village of Jungholz, south of the city of Kempten, Germany, is only connected to the rest of Austria at a single land point (a mountain peak). 

In order to enter Jungholz by car it is not at all necessary to touch the village of Wertach as it may look out from big-scale maps. One can just as well go there via Sonthofen. In fact the shortest road connection from the Austrian mainland to Jungholz does not lead through any considerable settlements in Germany.

Links:
«The boundary cross at Jungholz»: http://jungholz.enclaves.org/