Studies have found multiple layers of similar buildings with more regular features, prompting the theory that this "Republican Regia" was to have a different use.

[further explanation needed] According to ancient tradition it was built by the second king of Rome, Numa Pompilius, as a royal palace.

The archives of the pontifices were kept here, the formulas of all kinds of prayers, vows, sacrifices, etc., the state calendar of sacred days, the Annales — the record of events of each year for public reference — and the laws relating to marriage, death, wills, etc.

The rebuilt structure (which seems to have been transformed into a private residential building sometime during the 7th or 8th centuries) had an irregularly formed enclosed courtyard that was paved in tuff with a wooden portico.

[6] The East Room contained a sanctuary of Ops Consiva, so sacred that only the pontifex maximus and the Vestal Virgins were allowed to enter it.