Thanks to the long, paved path along the Vistula River, you can run for over 20 miles on the scenic waterfront bordering downtown Kraków. This is by far the most popular run in the city, and the wide multi-use route is in great condition throughout — it even has separate lanes for bikes and runners/pedestrians. While you can hop on and run a solid length at any point, the best (and safest) section is right downtown, between the Grunwaldzki and Kotlarski bridges making for a 4.5 mile loop.
Start out on the north side of the river near the Debniki bend and head east until you reach the bridge Kotlarski bridge at Grzegórzki Zachód. Pass the Smok Wawelski statue, Wawel Royal Castle, Church on the Rock, and the Ethnographic Museum, as you skirt the Kazimierz, the historic Jewish quarter and one of the coolest neighborhoods in the city (run up the Krakowska for a nice detour). Cross over at the Kotlarski Bridge, and return on the south side. The Józefa Piłsudskiego w Krakowie Bridge is worth a cross to see the hanging figurine-like sculptures.