“Never Forget” has been forgotten. A startling number of 9/11 monuments around the country have been vandalized or fallen into disrepair, including a $2 million Nassau County memorial. In Eisenhower Park in East Meadow, graffiti is scrawled across a section facing the wall of 10 plaques honoring 344 county residents murdered in the terror attacks. The empty fountain had condom wrappers; the base of a fountain displaying two 30-foot-tall aluminum towers is marred by peeling paint, while black marble tiles surrounding it are missing. Others are loose, some streaked with oozing white adhesive. “A lot of blood and sweat went...