Why are works of Livy considered to be so invaluable to historians?

Livy's works, particularly "Ab Urbe Condita," are invaluable to historians because they provide a comprehensive narrative of Rome's history from its legendary origins to the early days of the Roman Empire. His detailed accounts offer insights into Roman culture, politics, and society, reflecting the values and experiences of the time. Additionally, Livy's use of primary sources and critical analysis of events helps historians understand the complexities of historical interpretation, making his writings a crucial resource for studying ancient Rome.