The best and proper way to make optional subpath at the beginning of URL

[kolnogorov]

Hello!

I have a project with some city-dependent pages.
There are some cities with one default city. So, folder stucture could look like this:

.
└── pages
    ├── [city]
    │   ├── [services]
    │   │   └── [service].js
    │   ├── about.js
    │   └── contacts.js
    ├── city-independent-page.js
    └── other-page.js

So route should look like /london/about and /paris/contacts.

But i need to have one default city, whose pages should be accessible without city slug. Let's say, it's Moscow, so by default:

/about and /contacts should be opened under Moscow (but without moscow in url ), and /london/about or /paris/contacts should be opened under London and Paris as usual.

So, can I somehow make into this?

Thank you very much in advance!