Which Roman figure was responsible for the downfall of Troy?

The figure responsible for the downfall of Troy is Aeneas. In Roman mythology and literature, particularly in Virgil's "Aeneid," Aeneas is portrayed as a Trojan hero and a leader who escapes the burning city of Troy after its fall. Aeneas's journey from Troy to Italy is a central theme of the "Aeneid," which emphasizes his role as a progenitor of the Roman people.

His departure from Troy marks the transition from the city’s destruction to the foundation of a new future for his descendants in Italy, ultimately linking the Trojans to the origins of Rome. Aeneas embodies the values of duty and piety, and his actions set the stage for the eventual establishment of Rome, making him pivotal in the narrative surrounding Troy's downfall.

In contrast, the other figures mentioned do not have a direct connection to the fall of Troy itself. Julius Caesar is a historical figure from a later period of Roman history, Turnus is a character from the same epic who opposes Aeneas in Italy rather than being involved in the fall of Troy, and Romulus is credited with the founding of Rome but is also not linked to the events surrounding Troy.