Kaiserslautern is about 3 times smaller than Athens.

Athens (map shows its 34 named neighbourhoods; the area covers the whole city) is approximately 412 sq km, while Kaiserslautern is approximately 140 sq km, making Kaiserslautern 33.91% the size of Athens.
Tip: This to-scale comparison of Athens vs. Kaiserslautern uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.