Yesterday I was back to that spot.
I explored what I could, here are the results.
There are growing quite young trees.
They have 20 - 40 years.
You have successively:
000 Guide
001 From North to South
002 Some barrier
003 Concrete substrate
004 Stone
005 Several concrete blocks. In addition to the old road. Maybe the remains of demolished house.
008 The old road. From North to South
009 The old road. From South to North
010 - 014 Space between the roads
Without the metal detector did not we know what is underground.
Unfortunately, I do not have the detector...