Labels indicate where to park the front wheel of aircraft

Markings like this indicate a range of aircraft the airport has accommodated through the years. 

Frankfurt Airport (top) is one of Germany’s busiest airports. Most of the labels here indicate in-service aircraft and just a few that are no longer in service (MD11, DC10, L1011). They’ve added the B787 too.

Tegel Airport in Berlin (bottom) shows its age with markings of very old aircraft (B707, B727, MD80) as well as Russian aircraft (TU154).