Albergo diurno Cobianchi, Underground public bathhouse in Piazza Oberdan, Milan, Italy.

The Albergo diurno Cobianchi in Milan occupies a subterranean space beneath Piazza Oberdan, near the Porta Venezia metro stop. Its interiors, designed with input from Piero Portaluppi, belong to the Liberty and Art Deco styles. The facility housed public baths, barbers, hairdressers, a laundry, public telephones, writing and meeting rooms, a currency exchange and a travel agency.

Cleopatro Cobianchi opened the first day hotel in Bologna in 1911, at the Voltone del Podestà in Palazzo Re Enzo. The Milan branch under via Silvio Pellico, next to Piazza Duomo, followed in 1924; the one at Piazza Oberdan opened the next year, with Piero Portaluppi among the interior decorators. It stayed active until 1996, except for a hairdresser that held out until 2003, and was then recovered almost entirely for museum use, the only such case.

The facility served as a social meeting place for travelers and locals seeking bathing and grooming services that reflected early 20th-century values around public cleanliness and personal care.

The bathhouse functioned as a place where visitors could shower, get haircuts, and rest without needing to rent a hotel room. The underground space today is no longer open to the public, having closed decades ago.

Of the sixteen Cobianchi day hotels built, only the Milan one under Piazza Oberdan was recovered almost entirely for museum purposes, with a single hairdresser's shop holding out there until 2003. The others were dismantled, converted or emptied; in Rome only one sign survives, at the corner of Via Orazio and Via Cola di Rienzo.