The Palm House in the palace park at Schönbrunn Palace, Hietzing, Vienna. 

Commissioned in 1882 by Emperor Franz Joseph. Architect: Franz Segenschmid. It is the largest palm house on the European continent, consisting of 45,000 panes of glass. The Palm House is divided into three pavilions, each with its own climate zone, which are connected by tunnel-like corridors. 

Photos: Rhiannon Boyle, flickr.