According to Livy, his first act as king was to order the Pontifex Maximus to copy the text concerning the performance of public ceremonies of religion from the commentaries of Numa Pompilius to be displayed to the public, so that the rites of religion should no longer be neglected or improperly performed.
He commissioned Giacomo Della Porta to remodel the church and commissioned the construction of an aqueduct to supplement inadequate wells, for the abundant springs of Arsoli have been tapped to serve the city of Rome since 600 BC, traditional date of an aqueduct, built, according to tradition, by Ancus Marcius.
Tanaquil's prophecy was eventually realized for Tarquin - he eventually became friends with King Ancus Marcius, who made Tarquin guardian of his children.
But he clearly refers to Ancus Marcius, an ancient Roman king, who was said to have revived and completed the religious institutions of Numa after succeeding Tullus Hostilius.