Giovanni Battista di Quadro (Polish Jan Baptysta Quadro, Latin Joannes Baptista Quadro) (died between 10 April 1590 and 16 January 1591) was an Italian renaissance architect, one of the most famous architects in Central Europe in his era.
He was born Ponte Tresa or Cadro, near Lugano (today Switzerland).
Until 1550, he probably worked in Saxony and Silesia, but on 13 March 1550, he signed a contract with the city council of Poznań for rebuilding the town hall. In 1551, with the agreement of the council, he went to Płock as a consultant on the renovation of the cathedral. In the same year, his name was mentioned in the court books of Poznań because of links between him and the Bishop of Poznań Benedykt Izdebski relating to building the bishop's palace in Krobia. From 1552 to 1562, di Quadro was the City Architect of Poznań, but the City Council also paid him in 1563, 1566, 1567, and 1570 for minor works. During these years, he worked for the citizens of Poznań and the clergy and nobles of Greater Poland.
From 1568 to 1572, he worked in Warsaw, rebuilding today's Royal Castle.
His many well-paid jobs made him wealthy. However, after he retired in 1573, he died as an indebted person in Poznań.
During the years 1550-1552, his brothers Antoni, Gabriel, and Kilian di Quadro also worked in Poznań.
Works (existing and no longer existing) attributable to him, on analysis of style and unverified documents):