The Sign To The Endless Caverns In Virginia - 'Endless Caverns' sign. This is the sign for the Endless Caverns. It is on the side, of the Massanutten Mountain, in New Market, VA. It has been completely refurbished and lit for the first time in 30 years! I was 13, when it was last used. It was the saddest thing to see the dark sign as you drove by. This sign is the largest lighted sign in the United States.