It is an old Roman stone quarry and reminded me of the Bath stone workings. It is Lajta limestone. Quarrying apparently stopped in 1948. Parts of the quarry are open air and there are some underground sections. It is quite impressive with high ceilings and very white rock.
Read more on Fertorakos page.
See my next 2 blogs on Hungary, Tihany and Lillafured show caves and Aggtelek area.