A toy building set with toy building elements with coupling means for releasably interconnecting the toy building elements, which further comprises outer and inner toy building elements with a longitudinal direction. The inner toy building elements are receivable in the outer toy building elements, and the inner toy building elements are slideable in the outer toy building elements along their parallel longitudinal directions. The outer toy building elements can be interconnected in their longitudinal directions to form a composite outer toy building element, and the inner toy building elements can be interconnected in their longitudinal directions to form a composite inner toy building element that can be slideably received in the composite outer toy building element.