St Peter and Paul Fortress, St Petersburg, Russia, January 1993
Every January there is a memorial day for the 900-day WWII German Blockade of Leningrad, as St P was known for most of its communist years. Up to a million people died in the city, but it didn't surrender (or wasn't allowed to). This is the only regular fireworks event which happens when the night is dark, i.e. in winter; the others have disappointingly light "White Nights" skies.
The general technique for shooting fireworks at night requires a tripod and an open shutter. Keep a piece of black card over the open shutter between bursts of fireworks, and snatch it away when you want to record them. Expose as many as you want on a single frame, being aware that exposure is affected by this. It calls for some experimentation.