Mariahilf, the trendy 6th District, is bordered by Mariahilfer Strasse, a busy pedestrian strip with fashion and lifestyle stores. Vienna’s large outdoor market, the vibrant Naschmarkt, is a gourmet magnet lined with food stalls and eateries. A massive WWII anti-aircraft tower houses the Haus des Meeres aquarium. Neighborhood streets are dotted with edgy shops, classic Viennese coffeehouses and several theaters.