18 Market Square in Tarnowskie Góry, Historical house at Market Square in Tarnowskie Góry, Poland.

The house at 18 Market Square in Tarnowskie Góry is a three-story building on a rectangular plan with a gable roof whose ridge runs parallel to the market frontage. Its five-axis facade has a ground-floor arcade open through three arches, and inside, original cross-vault, barrel-vault, groin-vault and sail-vault ceilings survive, along with plank doors from the 18th and 19th centuries.

The house was probably built in the 16th century, though one source gives the 17th. Its first known owner, Bernard Bordolo, paid the quarterly and street tax in 1674. Around 1703 he likely designed the addition of a second floor, which a neighbour contested in court and lost in 1704. The building burned in the town fire of 1746.

The building's name is not recorded, but its owners are: city builder Bernard Bordolo, who likely designed the early 18th-century second-floor addition, and from at least 1909 Felix Ruttkowski, who ran a distillery, tavern and cigarette warehouse here. Agnes Ruttkowski continued the business in 1941. Today a sushi restaurant and a Ruch newsstand occupy the ground floor.

The building stands at the center of the marketplace and is easy to locate and approach on foot. Its central position allows visitors to view the facade and historical details from multiple angles.

The house preserves original vaults, including cross-barrel, barrel, cross and sail vaults, alongside plank doors from the 18th and 19th centuries. In 1872 it sheltered 20 people: the restaurateur Joseph Johann Sobtzik, his wife, four daughters, a servant and five other families.