I’ve been lucky enough to spend about 2 months in Piran in 2018, which explains the running coverage of the next map. The area is really great because you can easily mix speed and hilly sessions.
There is plenty of room to run, even in the most touristic streets, not a lot of traffic, so definitely a great place.

Classic

Starting from Piran, you can follow the coastline and go to Fornače, Portorož and Lucija, which is already a good stretch. If you continue and cross the camp site, you can follow the road along the canal, great landscapes are guaranteed.
In the other direction, you must first climb to St. George’s Parish Church, then follow a path leading to Fiesa lake.

Hors des sentiers battus

If there is one place I want to repeat, it is the Strunjan Landscape Park. There are several ways to go there from Piran, either by road or by trails. Once in the park you can really enjoy yourself, there are very steep roads that bring you to to high cliffs. I also enjoy exploring the Seča area, with views on the Sečovlje salt evaporation pond.

A few tracks I liked

Piran - Santjane - Strunjan - Fiesa: 15 km for 400 m of positive elevation, really a good choice to see a lot in one go.

Piran - strunjan - portoroz-strunjan: a nice loop following the coast for most of the time, it also takes the tunnel (for pedestrians and bikers) from Portorož to Carbonaro.