Welcome to the glory days of the Austrian Empire—and of summer. In a sprawling garden with old chestnut trees, beautifully preserved 19th-century changing cabins, coated in the characteristic imperial yellow (Schönbrunner Gelb), encircle gravel-lined pools filled with fresh cold spring water.

Popular with Vienna’s creative and media scene, Bad Fischau is a godsend on sweltering summer days. The thermal spa pools were opened in 1872, though the ancient Romans already availed of the mineral water, and the pools remained the property of the former imperial and royal Habsburg family until the ’90s. Today, water temperature remains a constant 19°C and a stream renews the pool water every three hours as an occasional trout swims through.

Forget gingerly leveraging yourself down the steps into the pool. We say the best way to acclimate is by boldly shock freezing yourself under the waterfall in the small cave—equal parts Thalasso therapy, hangover cure and instant face lift.