Each of Rome's legendary or semi-legendary kings was associated with one or more religious institutions still known to the later Republic. Tullus Hostilius and Ancus Marcius instituted the fetial priests. The first "outsider" Etruscan king, Lucius Tarquinius Priscus, founded a Capitoline temple to the triad Jupiter, Juno and Minerva which served as the model for the highest official cult throughout the Roman world. The benevolent, divinely fathered Servius Tullius established the Latin League, its Aventine Temple to Diana, and the Compitalia to mark his social reforms. Servius Tullius was murdered and succeeded by the arrogant Tarquinius Superbus, whose expulsion marked the beginning of Rome as a republic with annually elected magistrates.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): The removal of whom marked the beginning of the Roman Republic?
Tarquinius Superbus