Here are four archaeological discoveries that have had a major impact on the way we understand history:

1. **Discovery of Troy**: The city of Troy, described in Homer's Iliad, was long considered a myth. However, excavations led by German archaeologist Heinrich Schliemann in the late 19th and early 20th centuries revealed the ruins of a city that might correspond to the legendary Troy. This discovery provided tangible evidence of the existence of an ancient Greek civilization and raised questions about the historicity of myths and legends.

2. **Discovery of the Tombs of the Valley of the Kings in Egypt**: The tombs of the Valley of the Kings, located on the west bank of the Nile River near Luxor, were the final resting place of many pharaohs of the New Kingdom of Egypt. The discovery of these tombs, starting in the 19th century, including the famous tomb of Tutankhamun in 1922 by Howard Carter, has provided a wealth of artifacts and information about Egyptian civilization, its religion, art, and society.

3. **Discovery of the Lascaux Caves**: In 1940, four teenagers in southwestern France accidentally discovered the Lascaux cave, which contained some of the most impressive cave paintings ever found. Dating back to around 17,000 years ago, these paintings have offered valuable insights into the daily lives, beliefs and artistic skills of prehistoric people, redefining our understanding of the history of art and human culture.

4. **Discovery of the Mayan City of Tikal**: Tikal, located in the jungle of Guatemala, was one of the largest cities of the ancient Mayan civilization. For centuries, Tikal remained hidden by dense vegetation until it was rediscovered in the 19th century. Subsequent excavations revealed an impressive metropolis, with temples, palaces and ceremonial structures that provided crucial insights into the social, religious and political organization of the Mayans, as well as their interaction with other Mesoamerican civilizations.