Mercury (front view)

The most celebrated sculpture by Giambologna is the Mercury, known in four versions whose chronology is uncertain. His first design, a heavy wingless figure, is preserved in a model in Bologna. When Giambologna returned to Florence, he referred to his earlier work in a second version, a flying Mercury, now lost or identical to one in Vienna. This bronze was send by Cosimo as a diplomatic gift to the Holy Roman Emperor Maximillian II, when they were negotiating the marriage of Maximilian's sister Giovanna to Francesco de' Medici. The messenger god was Maximilian's protector and the pose was based on a medal of Maximilian by Leone Leoni (1551).

The fourth, a flying variant in Florence (shown in the picture) was completed by 1580, when it became a fountain figure at the Villa Medici, Rome. Mercury balances on a bronze column of air issuing from the mouth of Zephyr, over which flowed water, increasing the illusion that he was floating. The work shows a study of Verrocchio's Putto and Dolphin and Rusitici's Mercury, both for the Medici and is indebted to the Mercury on the base of Cellini's Perseus but has more dynamism.

The god assumes an arabesque, balanced precariously on his toes, and points upward to Jupiter. It is Mannerist in that it can be appreciated from all angles and is elongated and elegant; yet these features contrast with its amazing physicality and an evident study of weights and balances. The preciosity of "Maniera" is blended with what became Baroque illusionism and the freedom derived from wax.