First studies have been done by Vasile Parvan - 1915-1916 - then in 1958-1959. He though the earthen cliff and western cliff were conected, and described a wide bow to exterior 3 meters thick, that was built in brick; it has been destroyed for many times and rebuilt in the beginning of IV-th century, since there was built the so-called Butchers Tower (the butchers in town offered money for this wall part building). Two gates have been cleared up - they can be seen today in Ferdinand Blvd - and square towers guard them.