1 Monty: Romanshorn, on Lake Constance. Well, how are we going to get home from here?
2 Minnesota Jones: We're right across the lake from Friedrichshafen in Germany, where the Nazis build and test their zeppelins.
3 Prof. Jones: Are you thinking what I'm thinking?
3 Minnesota Jones: I think so...
4 Monty: What? That you're both deranged?

Friedrichshafen on the northern (i.e. German) shore of Lake Constance is where Count Ferdinand von Zeppelin oversaw construction of the first large rigid airships starting from 1899. The early zeppelins flew test flights over the lake. In 1908, Zeppelin founded the company Luftschiffbau Zeppelin GmbH to design, develop, and build airships. The company was based in Friedrichshafen.

Or should I say the company is based on Friedrichshafen. The name has changed slightly, but Zeppelin Luftschifftechnik GmbH is the direct descendent of the original Zeppelin company. And they still make airships.