On the actual days of the Kleine Zeitung Graz Marathons parking spots in the inner city of Graz can be scares. Therefore, it is recommended to park your car on the outskirts of the cities or in one of the P+R facilities of the city of Graz. You can find all of the Park&Ride possiblibities here: Park&Ride Possibilities
The journey to the start/finish area is best made by public transport of Holding Graz which is for free with your bibnumber on Sunday.
