Just north of the Church of Santi Medici Cosma e Damiano is the so-called Sovereign Trullo. Now used as a museum, it was built around 1796 on behalf of the family of the very wealthy priest Cataldo Perta and originally called the Court of Pope Cataldo. It is the most shining representation of the trullo’s construction technique, in fact, although it falls within the construction canons imposed long ago by Count Giangirolamo Acquaviva, it is the only trullo to be developed on two floors. With a 14-meter-high dome, the triangular pediment of the elevation rises to the second floor, which is accessed via a staircase ingeniously carved into one of the load-bearing walls. Declared a national monument in 1923, it was originally used as a seminary where the relics of Alberobello’s patron saints were kept before the construction of the Santi Medici shrine.