The Orthodox Cathedral Church of St Cyril and St Methodius (Katedrální chrám sv. Cyrila a Metoděje) was completed in 1736 in honor of the two saints who developed the Slavonic alphabet. In Baroque style, it is the work of architects Paul Ignaz Bayer and Kilian Ignaz Dientzenhofer, and it has an interior adorned with swirling floral frescoes by Jan Adam Schöpf.

However, the cathedral has another, more unexpected, claim to fame. In May 1942, Czech paratroopers were sent into Prague to assassinate the hated Nazi leader of Bohemia, Reichsprotektor Reinhard Heydrich. After wounding Heydrich (he died several days later), the partisans fled into hiding in the crypt of St Cyril and St Methodius but were betrayed to the SS and Gestapo. Realizing there was no escape, they committed suicide rather than be captured by Nazi troops. Later hundreds of innocent people in the Bohemian village of Lidice paid with their lives in retaliation for the assassination.

The intense bravery of the seven paratroopers involved in Heydrich’s death is marked with a permanent exhibition in their memory in the cathedral crypt, known as the National Memorial to the Heroes of the Heydrich Terror. The museum also tells the story of how the Czechs resisted Nazi occupation, and displays include maps, period photos and memorabilia.