Linz has an international airport (LNZ). From Linz airport there are three possibilities to reach Linz center:
Other international airports nearby Linz are Vienna
(VIE, 2 hours by train/car) and
3 hours by train/car). If you arrive in Vienna, take the Vienna Airport
Lines bus to Vienna West train station (Wien Westbahnhof) and then
continue by train. The bus stop is right in front of the airport
arrivals hall. Single fare: 6 Euro.
Download the Vienna Airport Lines bus timetable.
Linz can also be conveniently reached by train from Vienna, Salzburg, or Munich (Train connections can be looked up using the Travel Planner).