A picture from the summer here, that I found when looking for something else in my photo archive. Its the WW2 German K5 railway gun at a museum on Cap Gris Nez near Calais. I dragged the family there when we were early for our ferry.
The K5 is seriously impressive just for its sheer scale – the guns at the entrance of the Imperial War Museum are on a similar scale but aren’t mounted, so lack the impact.
For those who want technical details, its a 283mm calibre gun (~11″) that fired shells weighting 255 kg up to 50 kilometres.