|Bourtange Star Shaped Fort|
Acute angles on the corners of a building are added to the architectural design to eliminate "dead zones" in which an adversary could hide or take refuge. At the time of star shaped fortifications, all of the competing designs employed rounded towers or turrets at each corner, typically to house archers. As a breaching force approached the rounded corner, they were able to hide from the archers using the fortifications intended to be an asset in favor of the defenders.
Acute angles, however, prevented the breaching force from seeking shelter along the very walls intended to shelter the defenders. [See the illustration, below right.]
Modern applications against a well equipped modern adversary are very limited, since "air support" ruined traditional fort designs (adversaries can simply rain fire from above). However, against a low tech insurgency, the classic star design still prevails.
There are also applications for the acute corners in modern civil architecture.
For example, an HVT (High Value Target) person, such as a celebrity, bank CEO, or anyone else that might typically employ a Private Security Detail, these corners help to deter snatch-and-grab and similar attacks by simply limiting the avenues of approach. Col Jeff Cooper, famous for dealing with small arms fire, had a fascination with these acute angles to the extent that the term "Cooper Corners" was coined referring to this much older design.
In public civil architecture, there are obvious applications in places such as bank vaults, manufacturing facilities where the likelihood of espionage is high, and even public restrooms in semi-remote and semi-private, yet public places like city parks, where the likelihood of an after dark robbery or rape assault is high. In the case of the park (along with a well designed layout of lighting, landscaping, and shrubbery) the acute angles may be just the trick to eliminate lie-in-wait hiding places.
The next time you are tasked with securing a high value asset at a physical location, being familiar with the acute angles of the Medieval star fort might be the exact tool you need to pull out of your security toolbox.