Useful for fans of public fornication, and an absolute classic for first-timers escaping from the watchful eyes of their families, the concrete bunkers strewn over the Albanian countryside are infamous outdoor sex spots.
The former dictator Enver Hoxha established 750,000 of these indestructible domed love nests in the '70s and '80s, far more than could ever conceivably be used for his stated purpose, i.e., repelling invasion by capitalists or impure communists. Albania, with a population of only 3 million, thus has one bunker for every four people, and they are scattered everywhere. You will have no problem finding your own tank-proof concrete bower.
Be aware, however, that some do get used as lavatories as well, and the smell can be less than romantic.