Šargan Eight, Heritage railway in Mokra Gora, Serbia.

Šargan Eight is a narrow-gauge heritage railway in Mokra Gora that winds through mountainous terrain in a figure-eight pattern. The tracks climb 300 meters and cross the same location at different elevations while passing through tunnels and bridges along the route.

Austro-Hungarian engineers began the line during World War I to connect Užice with Višegrad, using Russian and Italian prisoners of war; a tunnel collapse at Budim hill in 1916 killed between 150 and 200 of them and halted work. Construction resumed on 1 March 1921 in the Kingdom of Serbs, Croats and Slovenes, when the figure-eight route was designed to overcome a 300 m descent. The first train reached Vardište on 25 January 1925.

The name comes from the track's figure-eight shape, designed in 1921 to climb 300 metres on short, curving sections; from Krst station it looks like two separate lines on two levels. The museum train "Nostalgija" runs with steam locomotive JŽ 83-173, and the route passes the Deveti Kilometar site, where a small memorial recalls the 1916 Budim tunnel collapse.

The line runs from Mokra Gora station to Šargan Vitasi, with the figure-eight section best seen from Krst station, where the track appears as two separate lines on two levels. The museum train operates in the summer season from April to October and in winter from 25 December to 25 January. The route passes through the protected Mokra Gora and Šargan nature park, and accommodation and catering facilities are available at the railway stations.

The route passes through 22 tunnels and crosses 10 bridges, allowing passengers to traverse the same hillside twice at different heights. This engineering solution lets steep slopes be conquered without making the line excessively long.