Knowing that Berg means mountain, I always assumed that cities such as Wittenberg, Wittenberge, and Perleberg (which is also my married last name) were named for nearby mountains. But there ARE no mountains in that part of Germany. Is it possible they're named for nearby hilltops? Or could -berg be an old misspelling of -burg?
According to german Wiktionary the word Berg has it origin in the proto-germanic word *bergaz which means Höhe (elevation). So in the beginning (9th century) an elevation in the terrain could be named "-berg".
And in the case of Perleberg apparently the elevation of 16 m was sufficient to call it "-berg".
The word Burg has it origin in the meaning of bergende Umgebung (protective environment). Note that bergen means recover.
And in deed, both words have a relationship in its origins in the meaning of Geborgenheit (security):
Berg = schützende, bergende Höhe = protective elevation
Burg = befestigte Höhe, befestigter Ort = fortified elevation or place
English hill translates into German Hügel but unlike in English speaking countries there are no cities, not even even villages but two named -hügel (Birkenhügel and Königshügel) and none … am … Hügel.
Perhaps because Hügel usually don't have a unique name in Germany. Or maybe because the most known Hügel are der Maulwurfshügel, der Idiotenhügel and der Grabhügel. (All these aren't good places to live at.)
What you see from time to time are hamlets on hills called -höhe.
All other places promoted their hills to be mountains a long time ago.
In addition, -berg is not a misspelling of -burg but as mountain tops are good places to build a Burg, there often existed a X-burg on top of a town named X-berg. This isn't the case for Perleberg, though, that Burg was named Gänseburg after the Gans family.