Wikipedia
Kronverk
The Kronverk ( Russian: Кронверк, from the German word for Crownwork) is a ground fortification for the Sts. Peter and Paul Fortress in Saint Petersburg, Russia. The Kronverk is situated on Petrogradsky Island, across the Kronverksky Strait from the Peter and Paul Fortress. It was built in 1705-08, with reconstructions in 1752 and 1800.
On 13 July 1826, five participants of the Decembrists' conspiracy were hanged on the eastern rampart of Kronverk (in 1975, an obelisk was installed on the supposed site of execution).