The short version: low rents on upper floors of Euljiro's working buildings created enough space for small bars, galleries, and studios to survive. The lack of signage isn't a marketing strategy — it's a neighborhood operating principle. And not every staircase you climb leads somewhere worth visiting.
How this actually happened
Euljiro's core building stock — mostly low-rise structures purpose-built for printing, metalwork, and electronics — has upper floors that machine shops don't need. Those floors rented cheap. From the mid-2010s, people with ideas and small budgets moved in. A bar didn't need a sign if it was running on reputation alone. Fact The word "Hipjiro" emerged from this period — but the buildings themselves predate it by decades.
What "no sign" actually means
A closed door in this neighborhood can mean a working machine shop, a bar that's not open yet, or a bar that doesn't want walk-ins. The sign-free aesthetic now exists on a spectrum: some bars have embraced it as an identity, others never had a choice. Either way, coming with an address, a floor number, and a reservation beats wandering hopefully up unfamiliar stairs.
Basic etiquette
Keep noise down — the floor below may be a print shop or metalwork studio. Don't bang on closed doors assuming they're bars. And read reviews first: not every "hidden bar" in Euljiro is operating, excellent, or worth the price. The neighborhood rewards preparation.