The observatory can easily be reached by car. It takes about 1 hour to drive from the center of Budapest. Driving out of Budapest one should take the M3 highway. Not far from the end-of-Budapest sign, take the M0 and then the M2 road, in the direction of Vác. Leave the M2 road at the exit Vác-Alsóváros, in the direction of Rád and Penc (right, east). Penc is the second village. In Penc, you will find the sign "Obszervatórium" where you should turn right (the third street on your right, called Mulató utca). The observatory building is about 3 km far away from this point uphill.
An alternative route is the national road no. 2 which leads to Vác in the northern direction along the river Danube. (The Budapest section of the road is "Váci út" - not to be confused with the famous shopping street "Váci utca"!) After passing Dunakeszi, Göd and Sződliget, and entering the town of Vác (35 km) turn right in the direction of Rád and Penc (east). Cross the railway line and drive an additional 15 km to get in Penc.