The Tongue and Groove Wooden Construction Set.

"This is the patented hardwood construction set made with precision-milled tongues and grooves for structures so sturdy they can be carried from room to room. A little downward pressure on the beams nestles them together far more securely than common wooden construction kits, so children can build structures that have the sturdy bearing of real castles and forts. The 187 beams and architectural detail elements in the kit can be used to make cabins, skyscrapers and bridges; even abstract or lopsided creations won't topple easily. When they want to share their work, children can pick up and carry the 11 3/4"" square base--tilting or even turning it upside down will not dislodge properly fitted structures. Made in Goshen, Indiana of select white hard maple--the highest grade--each piece is sanded to a finish so fine it requires no paint or varnish. Comes with a canvas drawstring tote for easy storage and portability. Ages 4 and up. (6 lbs.)"

It is easy to buy the The Tongue and Groove Wooden Construction Set. online. Hammacher Schlemmer has a secure server with quick and easy checkout.