Blue Markers: No longer original. Today there is a replacement bridge, or ruined remains- or it is missing completely. But there was a crossing on the old maps.
Maroon Markers : Intact original bridge dating to before 1750.
Red Markers : Intact original bridge dating to before 1600.
If there is no marker then it may be assumed that no bridge could be found on any of the old maps.
Ordnance Survey. Fully expandable to street level. Double click or roll mouse to expand. Or use the [+/-] in top left. Click/drag to move around. Click markers for bridge information. The red clusters open-up as the map is expanded.
For mobiles, suggest landscape view. Pinch/expand the [+/-] to enlarge the markers. Alphabetical List on the tabs is a useful alternative.
PLEASE NOTE THAT PHOTOS OPEN IN A NEW TAB