On an old SD thread, one poster from Vietnam noted that Ho Chi Minh City is almost never referred to by that name outside of formal documents. All other usage is by the pre-1975 name of Saigon. What other cities have widely used names that are not the official name, either by the locals or the world at large? And does the usage vary on political or other lines?
Well, there’s Istanbul or Constantinople (aka Byzantium).
But does anyone still use Constantinople in everyday usage?
Do names in other languages count? London, England, is Londres in French…
It’s nobody’s business but the Turks’.
Confusingly, the city of London and the City of London are two different places.
The Eastern Orthodox Church, but that’s about it.
Well, considered a places, the City of London is within the city of London. East London is far to the south of south London, however.
I bet there are Russians who still call St. Petersburg, “Leningrad” (or possibly even “Petrograd”), and I think I read somewhere recently that changing Volgograd back to Stalingrad is being mooted.
ETA: Here we are:
Are you counting things like where the name in English has changed but some people use the old one? Like Beijing/Peking or Mumbai/Bombay.
Yes.
No.
There actually still is a Saigon too. Ho Chi Minh City is divided into 21 districts – 16 urban and five rural. District 1 is still officially known as Saigon, and it’s here that many if not most of the tourist sites of HCMC can be found. (Many residents still referring to the entire city as Saigon tends to confuse things.)
Nobody refers to Kentucky’s second city by its official name, Lexington-Fayette.
Millions of people believe they have been in Las Vegas, but both the airport and The Strip are in Paradise, Nevada, and most people never leave Paradise and enter the city of Las Vegas while they are on the ground for their visit there.
The official name of Ventura, California is San Buenaventura. The city government mostly uses Ventura, but official documents and the city seal still say San Buenaventura.
Shawnee-Mission, Kansas, is a suburban Kansas City urban area with a population of 350,000, but does not exist as any kind of an entity, except as a postal address… It is widely used as a local reference, but actually consists of 15 cities and towns. All of them use Shawnee-Mission KS as their postal address.
El Pueblo de Nuestra Señora la Reina de [COLOR=“Black”]los Ángeles del Río de Porciúncula[/COLOR]
The City of London is surrounded by the city of London but it’s not part of it in the sense that Brooklyn is part of New York City or Montmartre is part of Paris. It’s a separate political entity with its own mayor, political administration, and police force.
All of London is made up of separate political administrations, many (all?) of which have officers called mayors. London is almost more like a US county than a US city. The City of London is unique in several ways but it’s definitely a part of the administrative entity of Greater London. If you live in the City of London, you vote for the London Assembly and the Mayor of London just like you do if you live in the City of Westminster or the Borough of Lambeth.
The strange thing being that the number of people who actually live in the City of London is negligible. But your point stands nevertheless. 
Spain is host to a few cities with multiple names, mostly due to the contrast between regional languages and the Spanish language. San Sebastián is often called ‘Donosti’ or ‘Donostia’; Lérida often called ‘Lleida’, and some people even call Pamplona ‘Iruña’'. Which version of the name you use is often a political statement.