An extension for building set number 28 (28A) includes 352 stone blocks in the three standard colors; brick red, natural sand, and slate blue. The Designs for Architectural Models booklet includes nine building plans for large and complex buildings including a renaissance museum, baroque cathedral, town hall, and royal stables. Packaged in a traditional wooden box for storage with a packing diagram and construction templates. This expansion allows you to build larger and more complex models. This set plus the combination for set #28 becomes the equivalent of set #30 and allows you to build all of set #30 models.