Stora Nygatan 17 ½, Neo-Rococo building in Inom Vallgraven, Gothenburg, Sweden

Stora Nygatan 17 ½ is a building in the Inom Vallgraven district, erected in the Neo-Rococo style to designs by master builder August Krüger and completed in autumn 1856. It originally formed part of a complex centred on the Gothenburg Synagogue. The ground floor held offices while the residence occupied the upper floor; the grand salon retains its white-and-gold Neo-Rococo interior.

August Abrahamson had the house built as part of a complex centred on the synagogue, and it was finished in autumn 1856, when he moved there from Kungsgatan. Robert Dickson bought the property in 1868. After Mrs Dickson's death in 1921, Försäkrings AB Amphion took over and added a storey.

The building's name comes from a planning oversight: two plots on Stora Nygatan shared a single street number, so the second house was given 17 ½. The white-and-gold Neo-Rococo grand salon survives as a room interior from the 1850s, restored after Fortia bought the property in 1971.

The building houses a psychiatric outpatient clinic today, so the entrance is a working healthcare facility rather than a public sight. The address sits on Stora Nygatan in Inom Vallgraven, and the 17 ½ number is easy to miss on the street. Look for the sister building at number 17 next door.

The half-number arose from a planning mistake: two plots had been laid out for the sister buildings at 17 and 17 ½, but only one street number existed, and the error was discovered too late. The result is Gothenburg's only address without a whole street number.