These are stone sleeper blocks, probably for fish-belly rails, some still have the cast iron rail chairs. The Stockton & Darlington Railway started off laid with these blocks. Eventually, the track became known as the "Permanent Way" ... Ignore the bit of modern "toy" track by the wall

Sadly, most people will not even notice these, as there was no visible interpretation.
However, I do know what they are !
I have seen these blocks reused in a number of places, including to edge slipways and beach access routes at the coast ...