11th November 17:10 update: It looks like all tickets are gone.
11th November 10:53 update: The booking system has been open for 30 minutes and tickets are going fast – so don’t be too surprised if you find zero tickets available for some of the locations.
‘Illuminate the Underground’ or ‘The Day Underground’ is running for the second year in Prague on November 25th and 26th 2017. On these dates, numerous hidden underground locations will be open to visitors for free. But you need to book in advance from today (11th November).
The current list includes (with links to the description in Czech):
Crypt of the Church of St. Cyril and Methodius – this is where the Czech paratroopers hid from the Nazis after the assassination attempt on SS-Obergruppenführer and General der Polizei Reinhard Heydrich, codenamed Operation Anthropoid. Resslova 9a near Karlovo námesti metro.
Tunnels 30m below the National Theatre (Národní divadlo).
Cold War Museum under the Hotel Jalta – Wenceslas Square (Václavské náměstí). I had to pay when I visited and it wasn’t really worth the fee. But go if it’s free.
The casemates at Vyšehrad – hidden spaces between the castle walls.
After that you’ll need to go out of the centre and choose one of the following – both at opposite ends of Prague
A tunnel beneath Divoká Šárka – Tunnel is 160 m with a width of 2.5 m plus home to 1200 bats!
Tunnel beneath Branická Skála – Tunnel is 250 m with a width of 2.5 m plus home to more bats!
The booking system is open from today (11th November) http://nadenpodzem.cz/
They also have a Facebook page: https://www.facebook.com/events/125753131431333/