These excavated timbers are relics of a Bronze Age causeway, thought to have been about a kilometre long, built across the Fens between 1350 & 850 BC.
On the wall at the back of this picture is an artists impression of what the causeway might have looked like. The blue sprinklers keep the timbers moist to prevent further deterioration.
You can visit the causeway and the Bronze Age log boats which are currently being preserved at Flag Fen in Peterborough. A fascinating day out in a remarkably peaceful spot. Well worth a visit!