Steiff-Fabrik, Toy factory and museum in Giengen an der Brenz, Germany.

The Steiff-Fabrikhalle is a 1903 factory hall of the Margarete Steiff GmbH in Giengen an der Brenz, known as the Osthalle or "Jungfrauenaquarium". Its facades are double-shell, non-load-bearing glass-iron curtain walls wrapping an internal steel frame, with a former ramp along the facade. A flat enclosed bridge with grid-paneled glazing and signs for Alligator and Steiff spans the driveway between the buildings.

Margarete Steiff started the business in 1880 making felt toys that quickly gained popularity. In 1902, the first jointed teddy bear was created here, an innovation that transformed the toy industry.

The glass hall was nicknamed the "Jungfrauenaquarium" (Maiden's Aquarium) because it was staffed mainly by unmarried women. In summer the glazing was coated with lime paint to keep the interior from overheating, and the paint was washed off later in the year.

The building is a working office site, not open to visitors; the former Steiff Museum moved to a new building in 2005. The facade ramp that once gave Margarete Steiff wheelchair access can be seen from the paved driveway outside. The bridge over the driveway carries the Alligator and Steiff signs.

Architecture critic Falk Jaeger wrote that the East Hall surpasses Walter Gropius's Fagus Factory in Alfeld in consistency. In 2011 Axel Föhl presented the East Hall in the ICOMOS annual journal as a possible candidate for a World or European Heritage nomination.