Turkey is a nation-state location on the planet Earth.  Located both in the European and Asian continents on Earth, the area had been an important center of human civilization for many thousands of years.
The largest city of Turkey is Istanbul, located in the northwestern corner of the country. The city - located on a strategic waterway - was known as Byzantium and as Constantinople before adopting its current name in the 20th century.
The city of Troy was located in Turkey. Up until the 1870s the city was considered a fiction to have been invented by Homer. During that time the ruins were discovered which established the actual existence of Troy. (TOS novel: Uhura's Song)
Additionally the city of Ephesus was located in western Turkey, near the modern Turkish town of Selçuk. One of the Seven Wonders of the Ancient World - the Temple of Artemis - was located within the city of Ephesus. Playing a memory game with Tom Paris, Neelix mentioned the temple while listing the Seven Wonders in order of construction. (VOY episode: "11:59")