One of my uncles (by marriage), an ex-seafarer, did fire-watch on the river-facing side of Liverpool's Anglican Cathedral's vast roof. Armed with a short shovel and a half-bucket of sand, he'd jog to and fro, pry flaring incendiaries out of the roof's lead sheathing before they could burn through.
He also had an excellent view of raids' progress.
Not as good a view as the spotters atop the cathedral tower, though. Their secure phone-lines to the famous underground control centre near Castle Street meant that even when street-level was in chaos, their reports allowed best use of resources, mapping of open routes. Down-side, if, like the unfortunate French cathedral, fire got set in the roof timbers, it would roar up the tower. The spotters knew they'd have to report as long as they could, then jump to quick deaths...
The Luftwaffe knew the tower was used for this 'C&C' spotting, many aircraft tried to strafe it. However, along the steep ridge behind the cathedral, there was a line of barrage balloons. The prospect of clipping a wing sufficiently discouraged such attacks...
Also, the Luftwaffe had promised fame and Iron Cross to the crew that managed to hit, flood the famous Mersey Tunnel. So, many bombs that would otherwise be dropped on ships, docks, rail-stations, warehouses etc went into the river. Even though the tunnel lay no deeper than a shallow submarine, all missed.
Mind you, the risk of catastrophic flooding meant that the main tunnel and its two branches could not be used as an air-raid shelter or factory, only as storage...