His main achievements include the project for the new city of Livorno, the decoration of Palazzo Pitti and the Boboli Gardens with the famous grotto, as well as the Parco di Pratolino of which little remains today, except for a giant sculpture by Giambologna, representing the Colossus of the Apennines.

Buontalenti's skills as a military engineer are shown by the fortifications of the port of Livorno, the Forte di Belvedere in Florence, the city walls of Pistoia, Grosseto, Prato, Portoferraio (Elba) and Naples; he also perfected designs for cannons, and devised a new type of incendiary grenade.

In the Uffizi Palace of Florence, he built a great court stage, where, during the winter of 1585–1586, splendid festivities were produced under his direction.

[1] Despite his successes, his prodigality led Buontalenti to financial ruin; he survived in his later life thanks to a pension given him by the Grand Duke of Tuscany.

In the Theater of Baldracca the stage would be raised a little, and the audience had to stand or to sit on long benches to watch the live performance.

Bountalenti and his pupil Matteo Nigetti were commissioned to build the Palazzo Nonfinito in 1592, but only the first floor was completed.