Many thanks to Yuri, who showed me the naval Cathedral of Kronstadt, which is a destination for pilgrims in memory of St John of Kronstadt.
There was a Eucharist service going on at the time.
Kronstadt is built on an island 30km West of St Petersburg, and is a naval base for the Baltic fleet.
It was in involved in the Revolution, the Kronstadt rebellion in 1921, was bombed by the Luftwaffe, and even attached during the Crimean war.
There are names of naval personnel lost in battles back to the Crimean war on tablets around the wall. This is just a small part of them:
Despite the fact that we built defences in Sydney harbour against the Russians at the time of the Crimean war, there was no mention here of sailors lost in action in Sydney!!