Hello,

The best cities to explore as per the source I had searched are

Moscow

St. Petersburg

Vladivostok

Irkutsk

Kazan

Other than that you will find 42 tourist places in arkhangelsk and orenburg is famous for its medical university.

Visit the following source link for more details :

https://www.expresstorussia.com/experience-russia/the-best-5-cities-to-visit-in-russia.html

Hope you find this useful.

Thank you!