(b Porlezza, nr Como, fl 1534; d Rome, 6 Jan 1577). Son or nephew of (2) Gian Giacomo della Porta. He also signed himself ‘Mediolanensis’ (i.e. of Milan): both signatures are found on the base of the seated figure of the tomb of Paul III. His father’s identity is still in dispute. Vasari describes him as the nephew of Gian Giacomo, a statement which biographers (Baglione, Soprani, Ratti) and later scholars have accepted; a document of 1561 identifies him as the son of a certain Cristoforo. However, in Genoese documents dated 1534–6, he repeatedly appears as the son of Gian Giacomo della Porta. This statement is the most convincing because it confirms that father and son worked together as partners, and because the style of works in Genoa known to be by Guglielmo continues in his works in Rome. The suggestion that a second Guglielmo della Porta was working in Genoa at the same time is untenable.

Part of the Porta, della family

• Porta, Guglielmo della (fl 1534-77)
  • Perino del Vaga
  • Rome, §III, 4(i): Art life and organization, 1503–49
  • assistants
    • Tetrode, Willem Danielsz. van
    • Torrigiani, Bastiano
  • collaboration
    • Corte, Niccolò da
    • Dosio, Giovanni Antonio
    • Porta, della: (2) Gian Giacomo della Porta
  • patrons and collectors
    • Aldobrandini: (1) Clement VIII
    • Pius V, Pope
  • pupils
    • Cobaert Jacob Cornelisz.
  • restorations
    • Farnese Hercules
  • works
    • Bernini: (2) Gianlorenzo Bernini, §I, 1(ii): Sculpture, 1623–44
    • Caro, Annibal
    • Equestrian monument, §3: High Renaissance and Baroque
    • Italy, §IV, 3(iii)(b): Mannerist sculpture, c 1530–c 1600: Rome
    • Porta, della: (4) Teodoro della Porta
    • Rome, §V, 14(ii)(b): St Peter’s: Decoration
    • Statuette, §II, 1(ii)(a): 16th century: Florence and Rome