"The cathedral was heavily damaged by a fire in 1595. The heavy bronze doors of the façade were newly designed, executed and completed in 1602 by sculptors around Giambologna on the expense of Ferdinando I de' Medici, the Grand Duke of Tuscany." The "wooden 17th-century coffered ceiling, painted and decorated with gold leaf, made by Domenico and Bartolomeo Atticciati [...] bears the Medici coat of arms."
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"Philip Il offered Siena to Cosimo I de' Medici, who merged it into his Grand Duchy of Tuscany while respecting its autonomy." (AB Ev) "To the west, the walls embrace the Fort of Santa Barbara that was rebuilt by the Medici in 1560 and finished in 1580." (Official description) "Siena's Fortezza Medicea (the Medici Fortress sometimes called the Fort of Saint Barbara) is a fort built in the city between 1561 and 1563 on the orders of Duke Cosimo, a few years before he became the first Grand Duke of Tuscany."
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Lorenzo II de Medici "in 1516, convinced his uncle, Pope Leo X to make him Duke of Urbino at the age of 24. So began a conflict with the city's previous duke, Francesco Maria I della Rovere. During the protracted War of Urbino, Delle Rovere recaptured the city, only to have Medici — commanding a 10,000-man Papal army — in turn, retake the city. During battle, Lorenzo was wounded, which prompted him to retire to Tuscany. In September 1517, he regained Urbino via treaty; however, it remained under the Medici family's rule for only two years. In 1521 the duchy reverted to the Della Rovere family."
See en.wikipedia.org

After its destruction by the Huguenots in 1564, Hautvillers Abbey was rebuilt thanks to the donations of Catherine de Medici.
See fr.wikipedia.org

The Last Judgement in the Sistine Chapel, painted by Michelangelo, was originally commissioned by Pope Clement VII, born Giulio di Giuliano de' Medici.
See en.wikipedia.org

Villa Medici

After the fall of Montalcino under the control of the Medici, the latter had the bastion of San Giovanni expanded and the tower of the Palazzo dei Priori raised, making them reach their current dimensions. In addition, the Medici, to obviously leave a mark of their dominion over the city, added the Medici coat of arms to many palaces and defensive works; an example is the Palazzo dei Priori.
See it.wikipedia.org

The construction of the Tuileries Palace started on the orders of Catherine de' Medici, who also created the Tuileries Gardens as a garden for the palace.
See en.wikipedia.org

The first part of the history of Montecatini ends in 1554, when the castle of Montecatini Alto was destroyed by Cosimo I de' Medici, Grand Duke of Tuscany (1519-74). (Nomination File, p. 432)

Medici Palace, Medici Tombs

On the left side of the basilica of Santa Maria degli Angeli is the Fontana delle ventisei cannelle commissioned by the Medici family of Florence and which is decorated with their coat of arms. There was already an aqueduct built by Cosimo il Vecchio, then renovated by Lorenzo il Magnifico in 1486 for the use of convent. (Nomination file, p. 44)