Frankfurt International Airport - Mainz Central Station
Least expensive option: At Frankfurt International Airport you can take the train to Mainz Hauptbahnhof, Regional Express, "RE" or the S-Bahn, "S8". After arriving at the airport, leave the station towards Zentrum. Look out for "Regionalbahnhof" signs (but not "Fernbahnhof"; note: "ICE", "EC" or "IC" trains are far more expensive). Below you can find instructions for buying a ticket at a local ticket machine. To check the traveling times take a look at the following link.
(1) Choose your language (A).
(2) Enter 65 for Mainz (B).
(3) Choose single trip for adult (C).
(4) Choose number 1 for Mainz via Rüsselsheim.
(5) Pay 3.80€ (D).
(6) Take your ticket and your change, if any (E).
Typically, trains are leaving at track 3 to Mainz, but please verify. Direction is toward "Wiesbaden". The safest is to take "S8". Exit at Mainz central station, i.e. one station after "Römisches Theater" ("Roman Theater"). A train map can be found here. For additional information regarding the local train system "Rhein-Main-Verkehrsverbund", click here
Other options:
Rental cars are available in Terminal 1, sections A and B, level 1 and in Terminal 2, section D, level 2 (Arrivals).
Check maps for traveling details.
Frankfurt Hahn Airport - Mainz Central Station
From Frankfurt Hahn Airport to Mainz Hauptbahnhof (main train station) you can take the Airport Shuttle Bus to Frankfurt (exit at "Mainz Hauptbahnhof", main train station). For further information about traveling times and fares please take a look at the following link.
Additional information on Frankfurt Hahn Airport can be found here.
Mainz Central Station - Johannes Gutenberg University
In front of the main train station, look for the bus stops F or G (to your right) which are located behind the "Ditsch" - snackbar. There you can take all busses to the university which leave almost every minute (check out possible bus lines here). Leave the bus at the stop "Universität" ( "H" denote bus stop signs) and go to the "Muschel" building ( E ). Note that bus number 69 takes you directly to the Campus (exit at "Colonel-Kleinmann-Weg"; bus line map). The following map shows the way to the building. Check maps for more traveling details.