A primate city is the largest city in its country or region, disproportionately larger than any others in the urban hierarchy
List all of the primate cities in Europe.
A primate city is a major city that works as the financial, political, and population center of a country and is not rivaled in any of these aspects by any other city in that country. Normally, a primate city must be at least twice as populous as the second largest city in the country. The presence of a primate city in a country usually indicates an imbalance in development (Wikipedia)
For example, Bangkok is a Primate city
Vatican is excluded as there are no real cities in the state.
On JetPunk, the widely accepted capital of Monaco is Monaco. I answered that and it did not work. I know that it is debatable, but the capital is usually considered as Monaco and not Monte Carlo, and Quizmaster along with the majority of JetPunk likes consistency. Please change Monte Carlo to Monaco.
Even though Turkey usually isn't perceived as European here on Jetpunk, Istanbul is largely located in Europe. It should be included, at least as an already given answer with a grey background.