Mysterious Symbols in your Walls?

From the AP:

It was a 3-foot-by-10-foot section of timeworn brick wall, its predictable rows abruptly interrupted by three distinct, deliberate-looking triangular shapes ... Painstakingly preserved from a 175-year-old building in lower Manhattan, the brickwork symbol is part of a tantalizing historical whodunit.

The triangle has traditionally been used to represent the Christian concept of the Holy Trinity. Some scholars, while stressing the need for more research, think the Pearl Street symbol evokes esotericism — efforts to delve for divine meaning in numbers, geometry, nature and elsewhere. The symbol was even the subject of a presentation at an academic conference on esotericism in Amsterdam in 2005.

And, if you want to see things that aren't there:

Alec Rawls' [book] documents a long list of Islamic and terrorist memorializing features in the Flight 93 National Memorial ... The primary feature, he says, is the giant central crescent of what originally was called the "Crescent of Embrace" design. A person facing into this half-mile wide crescent – still present in the superficially altered "Bowl of Embrace" redesign – will be oriented almost exactly at Mecca.

Reminds me of my own local library in Concord, New Hampshire, which supportedly has the Nazi symbol in its stone edging. It certainly does, but evidence of foul play? A sekrit Nazi plot to corrupt American youths who no longer know what a library is?