Levels near the N-entrance

A cross-section of the N-entrance at level 59,00 m followed by a staircase to the upper part of the main tunnel at level 55,83 m with an indication of the lower part at level 52,30 m. At the N side the levels of both parts of the main tunnel differ 3,50 m. Note: at the S-side the difference is 8,50 m (!!)
Shortly after the staircase the pipes enter from the W in a hall followed by a part with Roman and modern alteration: first with a vaulted roof, than a roof of iron plates, after that a gabled roof and than the original main tunnel, measuring 1,80 x 1,80 m