Two of the most imagination-firing sites in Wales, although you can't see anything.
The Severn/Hafren shoreline on the Gwent Levels has revealed evidence of Mesolithic seasonal visits. Although the shoreline itself largely follows the line it took 6,000 years ago, the land behind the flood defences was reclaimed from the floodplains initially by the Romans, so would not have been as dry as it is now.
At two sites, Magor Pill and Uskmouth, high tides in the 1990s revealed two sites that bring home the human story of this area vividly.
At Uskmouth (ST3482) three trails of footprints were found preserved in the intertidal mud. Two trails 10 metres apart run in parallel for 25 metres and are the footprints of adult men. The third trail is that of a child. From the prints the height and walking speed of the makers can be determined. A perforated antler mattock was found 370m SE of the footprints, at the same level.
At Magor Pill (ST4484), less than 10 miles up the coast, a single trail of footprints was uncovered 90m south of the present shoreline. The prints were larger and suggest a man with size 12 feet, standing just under 2m tall.
[Information all taken from "Prehistoric Sites of Monmouthshire" by George Children and George Nash (Logaston Press 1996).]