"Race you to the egg!" shouts Jasper, my 6-year-old son, as he starts tearing across the grass toward a group of smoothly carved boulders. A small sign says this granite sculpture, by Isamu Noguchi, is really called Momo Taro (after a Japanese folktale hero), but Jasper's name for it makes perfect sense: one rounded stone looks just like half a boiled egg with the yolk scooped out. Jasper and his cousin Campbell climb into the hollow center and peek out grinning.

We're at Storm King Art Center, a spectacular showcase of outdoor sculpture spread over 500-plus acres near the Hudson River in Mountainville, New York, just an hour outside New York City. Compared with the hushed formality of a typical art museum, this place is -- literally -- a blast of fresh air. We picnic under the trees, walk through rolling meadows (and hitch a ride on the tram when little legs get tired!), take tons of fun pictures, and discover dozens of creations as we wander the grounds.

"Who would have ever thought of that?" muses Lila, my 11-year-old, as she gazes up at a red steel zigzag rising nearly 70 feet into the sky, a sculpture called Endless Column by artist Tal Streeter. "It's so simple but so cool." The kids love reclining on Johnny Swing's Nickel Couch and Butterfly Chair, with seats made entirely of coins welded end to end -- and everyone is enchanted by Andy Goldsworthy's Storm King Wall, which meanders around trees, disappears into a pond, and then rises from the other side.

"Is that a sculpture?" Jasper keeps asking, surprised and impressed that such Dr. Seuss-like inventions are made by grown-ups who actually do this for their jobs. He's normally a bit hesitant to start an art project, but when the bold shapes of these monumental pieces inspire him to fill a pad with sketches, I know the outing has been a major success.