The ancient Greek city of Troy, famous for the Trojan War, is located in modern-day Turkey.

Explanation:
Troy is an ancient city that was located in what is now the northwestern part of Turkey. It is famous for being the setting of the Trojan War, an epic conflict described in Greek mythology. The city is believed to have been founded around 3000 BC and was inhabited for many centuries.

Troy's location in modern-day Turkey can be attributed to several factors:

1. Historical sources: The ancient city of Troy is mentioned in several ancient Greek texts, including the Iliad, a famous epic poem attributed to Homer. These texts provide descriptions of the city's location and its involvement in the Trojan War.

2. Archaeological evidence: Excavations conducted at the site of Troy in the late 19th and early 20th centuries confirmed its location in modern-day Turkey. The archaeological finds, including ruins of buildings, fortifications, and artifacts, have provided valuable insights into the history and culture of the ancient city.

3. Geographic considerations: Troy is situated on the western coast of modern-day Turkey, near the Dardanelles Strait. This strategic location made it an important center for trade and commerce in ancient times. Its proximity to the Aegean Sea also facilitated maritime connections with other Greek city-states and civilizations in the region.

4. Cultural and linguistic connections: The ancient Greeks considered Troy to be an integral part of their cultural heritage. Greek mythology and literature often refer to the city and its legendary heroes. The Greek influence on the region is evident in the names of nearby towns and landmarks, which have Greek origins.

In conclusion, the ancient Greek city of Troy, famous for the Trojan War, is located in modern-day Turkey. Its historical, archaeological, and geographical evidence supports its identification with the ancient city described in Greek mythology and literature.