Well, “flowering” is just how it struck me at first glance; it’s formally known as a star fort:
Palmanova was built following the ideals of a utopia. It is a concentric city with the form of a star, with three nine-sided ring roads intersecting in the main military radiating streets. It was built at the end of the 16th century by the Venetian Republic which was, at the time, a major center of trade. It is actually considered to be a fort, or citadel, because the military architect Giulio Savorgnan designed it to be a Venetian military station on the eastern frontier as protection from the Ottoman Empire.
Daily Overview adds, “The rationale for this construction was that an attack on any individual wall could be defended from the two adjacent star points by shooting the enemy from behind.” One of their commenters notes:
Additionally the angular shape of the walls relative to a surrounding force meant that incoming fire from siege artillery hit the wall at an angle or had to be shot further from an oblique angle, making it less effective.
(See all Orbital Views here)