ABC-Bogen, Office building in Neustadt, Hamburg, Germany

ABC-Bogen is an office building in Hamburg's Neustadt neighborhood composed of two linked sections. An eight-story front wing and eleven-story rear section reaching 40 meters tall contain retail shops on the ground floor and feature curved glass and metal facades that catch light throughout the day.

The site was occupied by the Hamburg State Archives, which had to relocate due to substantial damage. In early 1994 an investor was found for a land exchange, and an urban planning competition followed with six invited architecture firms. Hadi Teherani's design won unanimously, and construction ran from 1998 to 2000.

The rear wing's half-circle shape earns it the nickname "Zitrone" (lemon), a name used in everyday reference to the building. The front wing's wavy facade follows the line of the neighbouring Hypo-Bank building, and the ground floor holds shops plus the entrance to Google's German headquarters.

The front wing runs along ABC-Straße, while the rear "Lemon" stands in an inner courtyard reached via Fuhlentwiete, Hohe Bleichen and Amelungstraße. The ground floor holds several shops and the entrance to Google's German headquarters, so the courtyard side is not a public through-route.

The rear wing's curved shape means it casts almost no shadow on the neighbouring buildings, a deliberate effect of its half-circle plan. The front building's undulating facade follows the line of the adjacent Hypo-Bank building.