Sala Borsa, Art Nouveau library in Bologna, Italy.

Sala Borsa is a covered hall inside the Palazzo d'Accursio complex in Bologna, built between 1883 and 1886 as a cast-iron and glass pavilion in the Liberty style. Two upper galleries, added in 1924 to a design by engineer Francesco Tassoni, ring the covered square, and two underground rooms carry stucco and painted decoration with coffered ceilings. Since 2001 it has housed the city library.

The site began as a Roman settlement, then served as a botanical garden and telegraph office before becoming a stock exchange building in the late 1800s. Its Art Nouveau design reflects the architectural taste of that era when the building took its current form.

The name comes from its past role as a stock exchange, a place where merchants once gathered to do business. Today the space serves as a gathering spot for learning and community events, transforming it from a commercial hub into a place of public culture.

The library occupies the former exchange hall of Palazzo d'Accursio, entered from Piazza Nettuno through the semicircular exedra that serves as the access ramp. Two upper balconies, added in 1924, ring the covered square, and two decorated underground rooms hold the archaeology. The glass pavement over the excavations lies in the main hall, not at the entrance.

The glass floor lies in the covered square of the library, not at the entrance, and shows the stratigraphy of the site: Villanovan layers from the 7th century BC, Etruscan Felsina and Roman Bononia founded in 189 BC. Excavations also found the foundations of a large public building, probably the city basilica, at the crossing of the cardo maximus and decumanus maximus.