The Sweet Track in Somerset, Britain, was built exactly 5,828 years ago.
One thing you have to say about prehistory is that precise dates are hard to find. Hard to find is not the same as impossible, though.
In 3807 BCE, Neolithic farmers chopped down trees, mainly oak, to assemble a causeway. This ancient wooden trackway stretched from a ridge across a marsh to a nearby island, perhaps 2 kilometres from end to end. The track itself consisted of flat planks set on top of a series of wooden pegs; those pegs were stuck into the peaty bottom of the marsh in an X pattern:
Those farmers would have used the track for less than a decade before it got swallowed up by the boggy marsh. The track sat preserved in the peat for nearly six thousand years, until it was dug up in 1970. Because of that preservation, the tree rings on the planks allowed the track to be dated with startling accuracy. The oak trees had been felled in 3807 BCE, making the Sweet Track one of the oldest known pathways in the world.
(It’s not the oldest – the Sweet Track was built along the same path as the Post Track, which predates it by some thirty years, and since the discovery of the Sweet Track even older causeways have been discovered elsewhere in Britain.)