The capital of Bulgaria, Sofia itself provides some excellent opportunities for trail running on both paved and dirt surfaces. There is the obvious draw of Vitosha looming to the south of the city, but if you don't have the time or the stamina for a trip to Vitosha, Sofia's parks provide ample opportunity to stretch your legs.
Centrally located and Sofia's oldest park, dating from 1884, Borisova Gradina offers a variety of terrain plus both paved and unpaved paths. This park is super accessible and very near to Sofia University, Parliament and major hotels.
Meaning "Hunting Park" in Bulgarian, it is by far the least developed of the major parks in Sofia. It is also the least accessible but features a vast array of forested trails over mainly flat ground.
Probably the most popular park it Sofia, South Park is home to the original 5km along with the Spring 360. The vast majority of the trail are paved and offer beautiful view of Vitosha Mountain to the south. Terrain to the eastern side of the park rises steeply allowing for plenty of area of hill repeats, from gradual to steep.
West Park is easily accessible via metro and has some of the most varied terrain of any of the parks in Sofia. It has more recently become home to one of the weekly 5km runs. It is an excellent location to get in a quick long run with minimal overlap. Again trails are mixed between pavement and dirt various optional available.
As the name implies North Park is located at the very North(western) border of Sofia. It is partially developed and partially wild with a mix of trail and pavement. Easily accessible by two metro stops, the park provides for a bit of wild among some of the busiest residential areas of Sofia.