You could use this site: https://pleiades.stoa.org/.
It is a great tool which provides data about ancient names of cities and places. It gives scientifically approved coordinates of places, detailed informations about their names and further bibliographical references.
Here is the city of Marʿaš with all the names along the ages. As you can see, they changes through the centuries:
Caesarea Germanice (30 BC - AD 300)
Germanicia (30 BC - AD 300)
Germanikeia (30 BC - AD 640)
Germanikeia (140 BC - AD 1307)
Germanikeia Kaisareia (30 BC - AD 226)
K. Maraş (AD 1918 - AD 2000)
Kahramanmaraş (AD 1918 - AD 2000)
Marasch (Attested dates needed)
Maraş (1750 BC - AD 2000)
Maraš (1200 BC - 1199 BC)
Mariscum (AD 1081 - AD 1291)
Marqasi (1200 BC - 330 BC)
Marʿaš (1200 BC - AD 1922)
Marʿaš (1200 BC - AD 1922)
The ancient nominatives of the latin names are:
1) Caesarea Germanice (1st declension)
2) Germanicia (1st declension)
while Mariscum is the nominative (2nd declension) of the medieval latin name of the city.