The starfort first appeared in Italy at the end of the 15th century. Medieval-era fortifications tended to be ring-shaped, which not only allowed attackers relative safety when they got close to its walls, but were vulnerable to the new technology of artillery.
The design of the starfort did away with "dead zones," or areas in which an attacker cannot be brought under fire, by the use of triangular bastions which command all approaches. The starfort concept was adopted by nearly every European nation and in the New World from the 16th through 19th centuries. Starforts.com exists because starforts are really cool! Their symmetric beauty and historic nature make them absolutely fascinating.
The mission of Starforts.com was initially to be the definitive list of all the world's starforts...and while I would suggest that this site does boast a pretty impressive list, listing every single starfort is likely an impossible task, because one thing that I've learned over ten years of researching them is that starforts are everywhere! There are probably more used-to-be-starforts than there are starforts that we can see on Google Maps (or in person) today...please note that this site does not even attempt to chronicle starforts that were once, but are no longer.