> One of its major summer events is the Secret City Festival—a weekend of parades, concerts, and tours of the federal facilities. “It’s the only time during the

> One of its major summer events is the Secret City Festival—a weekend of parades, concerts, and tours of the federal facilities. “It’s the only time during the year that the public can gain access,” Smith says. From the article. This sounds like it's not publicly accessible 51 weeks of the year. Shouldn't that explain it? :)