Siena’s Fortezza Medicea 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.
The fortress is positioned on the northern edge of the central Siena in the Terzo of Camollia, in the neighborhood of San Prospero, and since 1923 has overlooked the city’s Artemio Franchi/Montepaschi Arena.
Wikipedia https://en.wikipedia.org/wiki/Fortezza_Medicea_(Siena)
Address 6 Piazza della Libertà, Siena 53100, Italy
Coordinates 43°19'20.114" N 11°19'24.12" E