From Utrecht Central train station, take bus 11 or 12 to "De Uithof". There is one bus every 5 minutes or so.
BUS 11: You have to get out at the stop called "Botanische Tuinen" (Botanic Gardens). The trip takes ~15-20 minutes.
BUS 12: You have to get out at the stop called "Kruytgebouw". The trip takes ~10-15 minutes.Here is a map of the university campus. The lecture
theatre (Grote
Zaal Aardwetenschappen, or "AW-groot") is located at the blue
solid
dot. Follow the blue arrows from the bus stop of either bus 11 or 12 to
the entrance of the Minnaert building (see picture below). Go up the
stairs
to the first floor of the Minnaert building. At
the top of the stairs, turn right immediately and cross the covered
footbridge leading to the
adjacent building of the Geosciences Faculty (Aardwetenschappen). The
lecture theatre is right in front of you!