[Ajef]

Having a name with "of Region/city/former kingdom/..." is often their last name. Unless you want to claim that these people do not have a last name.

I can understand that in some cultures this might seem weird or antiquated but here in Germany these names are reality. Sometimes people with such names are descendents of royalty and sometimes someones last name "from family-name" is thier last name and happens to historically correspond to one of germany's state names or city names or just a little town.

One a side note: In Germany in 1919-1920 royalty was no longer a legal aspect that changed how laws applied to you[1]. When that happened titles that were reserved for ruling functions (king, grand duke) were removed and all other titles were moved to be part of the persons name (such as prince etc.) and could not be decreed on anyone new. These titles still exist in Germany but are simply naming "conventions" in a formerly royal family.

[1] https://de.wikipedia.org/wiki/Adelsrecht

[edit] In Leonardo's case perhaps not but still i wish to elaborate a litte on the situation here.