From the Airport:
The City Airport Train, CAT, will take you to the city centre, Station Wien-Mitte in about 16 minutes. Departures every 30 minutes. Underground U4 direction Heiligenstadt to station Schottenring, change to U2 direction Karlsplatz to Schottentor, Hotel de France.
From Bratislava Airport:
Together with its partner Slovak Lines, the Postbus offers attractive connections 17 times a day from Vienna Südtiroler via the Vienna Airport to the Slovakian capital Bratislava.
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The Schnellbahn S7 (train) will take you to Wien Mitte/Landstraße. There you have to take Underground U4 direction Heiligenstadt to station Schottenring, change to U2 direction Karlsplatz to Schottentor and follow the signs University.
From West Railway Station: (Westbahnhof)
Underground U3 direction Simmering, change at Volkstheater into Underground U2 direction Aspern and get off at Schottentor and follow the signs.
From South Railway Station: (Südbahnhof)
Tram D direction Nussdorf to Schottentor, opposite the Hotel de France.