I continue my archeological search.
On topographic maps of my region, I'm looking for places where may be unknown hillforts. Then I go on the spot to see if there are signs of old fortifications. If so, I make a small file that I send to an archeologist.
I discoved so 3 unknown hillforts.
The necessary qualities are patience ( more than 9 times out of 10, there is nothing) and the "meaning" of the the landscape (after 2 or 4 thousand years, the ruins are really in ruins).
But I like this treasure hunt.