▁Bab ▁Sem marine ▁was ▁the ▁S idi ▁Bou ▁N af a ' ▁neighbourhood , ▁tradition ally ▁inhab ited ▁by ▁Muslim s , ▁which ▁was ▁ad jo ined ▁by ▁a ▁Sa ad ian - era ▁bast ion ▁of ▁the ▁same ▁name ▁and ▁whose ▁outline ▁can ▁still ▁be ▁made ▁out ▁today . ▁However , ▁from ▁Bab ▁Sem marine ▁a ▁street ▁desc ends ▁south ▁and ▁west ▁through ▁this ▁neighbourhood ▁until ▁it ▁reaches ▁Bab ▁el - M ella h , ▁a ▁gate ▁set ▁inside ▁a ▁bor j ▁( a ▁large ▁tower ▁or ▁bast ion ) ▁which ▁marked ▁the ▁official ▁entrance ▁to ▁the ▁M ella h ▁proper . ▁ ▁Bab ▁el - M ella h ▁originally ▁had ▁a ▁bent ▁entrance ▁but ▁now ▁has ▁a ▁straight ▁passage . ▁Despite ▁the ▁modification , ▁the ▁area ▁near ▁it ▁is ▁believed ▁to ▁be ▁the ▁oldest ▁part ▁of ▁the ▁M ella h . ▁Just ▁south ▁of ▁the ▁gate , ▁inside ▁the ▁boundary ▁of ▁the ▁M ella h , ▁is ▁the ▁S lat ▁al - F ass iy in ▁Syn agog ue , ▁believed ▁to ▁be ▁the ▁oldest ▁syn agog ue ▁of ▁the ▁district . ▁West ▁of ▁Bab ▁el - M ella h , ▁the ▁street ▁from ▁Bab ▁Sem marine ▁continues ▁and ▁constit uted ▁the ▁main ▁street ▁and ▁sou q ▁( market ) ▁area ▁of ▁the ▁M ella h , ▁and ▁was ▁also ▁called ▁Der b ▁al - S ou q ▁(" St reet ▁of ▁the ▁Market "). ▁Origin ally , ▁the ▁street ▁may ▁have ▁been ▁much ▁wider ▁originally ▁and ▁consisted ▁of ▁a ▁large