St-Louis-du-Ha! Ha!, Québec. The only place name in the world containing two exclamation marks.
Customers may use vanity addressing when providing a place name, giving a name which is perceived to be better instead of the correct one, such as Windsor instead of Slough, Scheveningen instead of Den Haag and so on.
In larger cities customers may provide the district or borough name instead of the city name, such as Camden instead of London, Kreuzberg instead of Berlin, Manhatten instead of New York and so on.
It is common for places to have multiple names: amongst the locals, in different national languages and/or in different non-local languages; and this variation is increased with casing differences, different uses of diacritical marks and punctuation, and so on.
Example: Names in different (non-native) languages: Cologne, Keulen, Colonia.
Example: Names in different (national) languages: Genève, Genf, Ginevra.
Example: Names in the same language: 's-Gravenhage, Den Haag
Example: Name in the same language, but written in alternative ways: Köln, Koeln, Koln.
Place names are often not unique, within a country or globally.
Place names can and should be standarised within postal addresses, but as there are often more than one populated place with the same or similar name in a country, this should be done using additional corroborative information, such as the postal code or an administrative district name.
Allow punctuation to be stored with place names.
Always stored the localised (local language) form of a place name, with the correct diacritical marks and punctuation. There is no good argument for using other language versions, and it shows an immense lack of respect to its inhabitants so to do.
Place names may be, or contain strings which are, regarded as obscene. Obscenity filters need to be careful about how place names are screened.