One of the most unique attractions in the Gorenjska region is the WWII-era tunnel complex that runs for 1.3km under the heart of Kranj's old town and was built to serve as a bomb shelter. Construction commenced in the late-1930s, but most of what exists today was carried out by occupying forces in 1944. An important piece of the country's historical and technological heritage, extensive restoration works were undertaken in the early 2000s and the tunnels opened to the public in 2008. The tour also includes a spine chilling simulation experience of an aircraft attack. Whilst this does give one a glimpse of the past it is perhaps not for the fainthearted.