With glass walls that can soar as high as 50 feet, Palmenhaus is dramatic, but it's also a quiet and calm place smack in the heart of Hapsburg-era Vienna. As the name suggests, the Palmenhaus is a greenhouse of the variety that nations of the 19th century were so good at creating to show off palms and other exotic plants plucked from the colonies. And thanks to a $17 million renovation in the 1990s, yes, Palmenhaus still has palm trees and tropical flora, as well as a lepidopterarium, or butterfly house. As Vienna’s palm house looks over the lush Burggarten park, its broad terrace makes for the ultimate spot to sit under sunny skies and sip a riesling or quaff a beer. On summer Fridays, DJs and live musicians perform.