The Archivum de Piro comprises an extensive private family collection of documents and records and is an extremely important historical record of business, lawsuits and marriage in the 17th and 18th centuries.

Grand Master Perellos ennobled the de Piro family with the Barony of Budach in 1716 and later in 1742 Philip V of Spain created Gio Pio de Piro, the 1st Marquis de Piro. The 1st Baron and 1st Marquis was a lawyer. There are surviving bills of lading as well as bills for transactions in which Giovanni Pio de Piro is selling Muslims to a Muslim trader called Raïs. There are hundreds of documents relating to the running of the Maltese state palaces. He invested in land, ships and cargoes of textiles, grain, sugar, rice, coffee and cocoa. In the various cupboards are seals, documents, pens and other items of interest.

On the table in the middle of the room is the carved wooden statue of St Paul, patron saint of Malta. This 17th century carving is probably the model for the famous statue of St Paul by Melchiorre Gafà in the Church of St Paul Shipwrecked in Valletta. Note the snake at St Paul's feet: this is to emphasise the story of his arrival in Malta described in the Acts of the Apostles. The legend is that since Paul was bitten, there have been no poisonous snakes on the islands.