Prague

Prague was a city in Czechoslavakia, in Europe on Earth. Throughout his many incarnations at least 8 incarnations of the Doctor visited the city.

In the 30th century, the Fourth Doctor and Romana visited the city and discovered that Charles University was experimenting with Zygma energy. (ST: The End of Now)

The Eighth Doctor and Charlotte Pollard once visited the city at a time when the city was enclosed within a dome. (ST: War in a Time of Peace)