Aboard the Singapore Flyer. I reckon there should be space for a mini-milonga in one of those carriages (or simultaneous milongas in each of them)
By the sea, like here in Scheveningen, The Hague. But not on a windy day (the sand gets in your eyes)
through Brandenburger Tor (and then all the way along to the Siegessaüle ..)
Years ago there used to be an outdoor milonga close to the Museumsinsel and these pillars outside the Finance Ministry on Leipzigerstr in Berlin reminded me of that. The milonga was called "Tango unter den Kolonnaden"
Potsdamer Platz, Berlin
Berlin main train station
Patio andaluz, Parque Rodó, Montevideo
Bandstand opposite the Puente de la Mujer, Puerto Madero, Buenos Aires