What is the fine-grained topic of the following text: For our final year in Montpellier, I had my friend Storm take me to Potsdamer Platz S-Bahn station in Berlin, which was a legendary practice space for b-boys from the city; much like the Piscine Des Halles in Paris, or the Charing Cross subway passage in London, facing the reflective glass of a restaurant called The Tappit Hen. Only return the topic.
Visiting famous practice spaces for b-boys in different cities.