Legend holds that Helen of Troy was so beautiful that men pledged their loyalty to her with such fierceness that they would go to war for her hand in marriage. Such oaths reportedly led to the invasion of Troy and the Trojan War.

Thucydides is considered one of the fathers of modern history. Unlike Herodotus, whose tone was very familiar, Thucydides was more dry and tried to stick to objective facts. He was, however, an Athenian soldier during the war, which colored his account of the conflict.

Nero, seeking pleasure, paid for and built the so-called Bathes of Nero. The largest baths in Rome, they were still in use up to the 5th century. While other Roman landmarks came and went depending on economic and political stability, the longevity of the bathes, as well as their complexity, set them apart. 

The Colossus of Rhodes was one of the most impressive structures in the ancient world. Originally erected to celebrate a victory over the island of Cyprus, the Colossus stood over the island's harbor for thousands of years. It was destroyed by an earthquake in 226 BCE, never to be rebuilt. 

The Aeneid, written by Virgil, it considered one of the most important works in Roman literature. Telling the story of Aeneas, who traveled from the ruins of Troy to the Italian peninsula, the Aeneid stands as the Roman response to Homer. This seminal work is still read in Classical Literature and History classes today. 

The Oresteia, Aeschylus' trilogy of plays detailing the fall of the House of Atreus, is one of the finest examples of Greek tragedy. Starting with Agamemnon's murder at the hands of his wife and finishing with Orestes, Agamemnon's son, being tried for the murder of the aforementioned wife (and Orestes mother), the plays explore the themes of justice, revenge and family like few other works. Extremely popular from the time of their first performance, the cultural impact of the Oresteia can still be felt today. 

Written as a conversation between Socrates and Glaucon, the Allegory of the Cave is one of the more famous ideas presented in his Republic. Positing that man sees reality like a man trapped in a cave sees a shadow, the Allegory of the Cave invites us to admit that not only do we not see the whole of reality, it would be nigh impossible to see the whole. The allegory continues to find new life today as it lives on in Western thought and culture. 

Oedipus Rex is one of the most popular of the ancient Greek tragedies. Chronicling the rise and fall of Oedipus, king of Thebes, as he goes from popular king to blind beggar. Sophocles regarded it as the great Greek tragedy, and his masterwork; history tends to agree with him.  

The Hagia Sophia was built in Constantinople in 537 CE, during the reign of Justinian I. For several hundred years it served as a church of Eastern Orthodoxy, and was the seat of the Patriarch of Constantinople (sort of like the Pope of Eastern Orthodoxy), until it was converted into an Islamic mosque, following the Ottoman conquest of the city in 1453.

Qin Shi Huangdi, who ruled as the only emperor during the short-lived but immensely important Qin Dynasty, ordered the construction of the Great Wall of China and the Terracotta Army. The Great Wall of China was built to prevent barbarian invasions into Chinese territory. The Terracotta Army was built for the slightly less practical purpose of furnishing the emperor with an army for the afterlife. The Grand Canal was built during the rule of the Sui Dynasty to connect northern and southern China. The Forbidden City was built during the rule of the Ming Dynasty and served as the seat of the imperial government until the Chinese revolution in the early twentieth century.