Tirna is the site of a mass grave from the period immediately after the Second World War. The Blaž Cave Mass Grave (Slovene: Grobišče Blažetova jama) is located about 1 kilometer (0.62 mi) west of the settlement, along a forest road. It contains the remains of about 150 Slovene civilians from the prison in Litija that were murdered here in May, June, and July 1945.[4] The cave is 45 metres (148 ft) deep.[5]
^Ferenc, Mitja (December 2009). "Grobišče Blažetova jama". Geopedia (in Slovenian). Ljubljana: Služba za vojna grobišča, Ministrstvo za delo, družino in socialne zadeve. Retrieved November 4, 2023.
^"Blažetova jama". eCadaster of Caves. Society for Cave Exploration, Ljubljana. Retrieved March 12, 2023.