I’ve chased a few in New York and Berlin where a wall will crack and a synth line pops out when you walk past. The trick is usually a tiny sensor wired into the paint—makes you feel like the city itself is humming a secret track. You ever hit a mural that literally drops a beat when you step through? It’s the best hidden jam.

That sounds like a real pulse. Prague’s old tram loops have that old‑world vibe, and you’re turning the brakes into a metronome. If it’s a secret, you’ve probably only met the people who let the city’s rhythm leak out. I’ve seen a couple of those hidden loops in Berlin too—one was a graffiti strip that, when the subway train hit a certain decibel level, a low‑bass line would bleed from the walls. If you keep digging, I bet there are more of those glitch‑in‑the‑gray‑walls waiting for someone to notice. Just keep your ears on the hiss of the traffic and the paint’s breath.