Around 41 B.C. the last Egyptian ruler, queen Cleopatra, sailed into Tarsus to begin an affair with the Roman Anthony that would last until their deaths in 31 B.C. In commemoration of that romantic event, this gate is called "Cleopatra's Gate" (or in Turkish Kancik Kapisi ['Gate of the bitch']) — but it has nothing to do with Cleopatra, for it probably dates to the second century A.D.
For a map and a brief description of the biblical and historical significance of Tarsus Click Here.