Denizli did not start where it stands now. The first town was about six kilometres north of the modern centre, near the village of Eskihisar; after the Turks took the district they moved the centre to the Kaleiçi site, because the water there was plentiful.

The name has never settled either. Seljuk records and the court registers of Denizli call it Ladik. Ibn Battuta, writing his travels, calls it Tonguzlu, and the same form appears in the Mesâlikü'l-ebsâr. Şerafeddin Yezdî, who wrote Timur's book of victories, gives two forms, Tenguzluğ and Tonguzluğ. Tengiz is the Old Turkish word for sea, and Tengüzlü is Denizli in modern spelling — but the Ministry of Culture's own account stops short of calling any one of these the answer, and says the forms probably shifted from mouth to mouth into the name used today.