Seeping through the cracks of a concrete ceiling cluttered with pipes and bare wires, water accumulates into a puddle in the middle of a murky passageway lined with antiquated pubs, ethnic eateries, a psychic parlor and vendors selling cheap wrist watches and pornographic DVDs.

An elderly woman vacuums up the pool with an air of resignation as pedestrians brush past her toward the ticket gates of an adjacent subway station, likely unaware that they’re plodding through Japan’s oldest-surviving underground shopping street, established in 1955.

The hordes of tourists aboveground may be oblivious to it, but this subterranean arcade in Tokyo’s traditional shopping and entertainment district of Asakusa retains a heady dose of Showa Era (1926-89) nostalgia and stands testament to a period when the capital dug deeper and deeper to develop a massive underground network of infrastructure to serve its burgeoning population.