Decorated hagstones, or adder stones, believed by Druids to have magical powers such as protection against eye diseases or evil charms, preventing nightmares, curing whooping cough, the ability to see through fairy or witch disguises and traps if looked at through the middle of the stone, and of course recovery from snakebite. According to popular conception, a true adder stone will float in water.
Architecture is creativity solidified into a form of building..."the complex or carefully designed structure of something" (Google def #2). NOT necessarily as large as "a building". Here is a half-circle of stones built to rise in an arch at the still water's edge. The waters reflect it to create a perfect circle, and the stones below the water parallel the form of the stones. Martin Hill Stream Stone Circle, White Beach, New Zealand