I use running during tours to relax, stretch out and get some aerobic activity in while seeing an interesting part of a city. Because of the demands of the tour schedule, much of it must be done in the morning before travel or rehearsal.
Many European cities are situated along major rivers. Much of the time there are dedicated paths along them for bikers, walkers and runners.
During our stay in Linz I ran along the Danube using the Danube River Bike Route
This is part of a route that stretches from the Black Forest in southeastern Germany to the Black Sea. I've run along other stretches of it before in Vienna and Belgrade.
The section from Passau, Germany to Vienna (about 200 miles) is considered the best part of the route. Here there are no roads to share with vehicles. In some places there are paths on both sides of the river.
In the Linz area there are kilometer markers telling you how far it is to the next city, how far to a place for public showers, signs for hotels, B & B's, campgrounds, etc. that cater to the bikers
To get to the path I just headed to the river from our hotel and crossed using a big railroad bridge. Great views of the city, countryside and Danube all around.
This was not the case in Belgrade, however. After the trail leaves Austria, the path is not marked with attractions and bikers must use city streets from time to time. We ran through an industrial shipping area in Belgrade that felt rather sketchy.