From the Gateway Arch in St. Louis to the Arc de Triomphe in Paris to our very own Washington Square Arch, the curved symmetrical formations known simply as arches have a way of lending a certain cachet to even the most mundane structures. And though there is nothing remotely mundane about this sprawling Tribeca loft at 108-110 Franklin Street, its six fully revealed foot-and-a-half-thick brick archways elevate the home’s natural beauty to a new level. Six gorgeous arches this way