The Wien Mitte train station is the central hub connecting the train lines S-Bahn with a metro train system named U-Bahn. Look for U Bahn signs leading to the Landstrasse U-Bahn Station. Look for the ticketing machine to purchase the ticket. U-Bahn tickets are as follows: Day Ticket Vienna is valid on all public transport services in Vienna for one day from the started date until 1.00 am on the following day. (5.80 euros) 24-h Vienna ticket is valid on all public transport services in Vienna for 24 hours from the stated date and time. (8 euros) There are a variety of tickets, including the 48 and 72 hours tickets, weekly card and so else all are available at the ticketing machine.
Photo Von Gugerell - Eigenes Werk, CC0, https://commons.wikimedia.org/w/index.php?curid=26451702
How to get from Vienna Airport to the Kaiserhof hotel by public transport? Train from the airport to the Mitte Vena central transport hub, continue by metro two stops to Kaiserplatz, and five minutes walk to the hotel. The fare is about 10 euros.