The Medici Tower next to the Bourse de Commerce de Paris. Catherine de Medici installed it for her personal astrologer, & Ruggieri, in the 1570's. (Cosimo succeeded the infamous Nostra­damus, who accurately predicted the death of the Queen's husband, Henry III, in 1559.)

For more on Context Tours, go here, and for details about the Belly of Paris tour, go here.