Sis forSandcastle
A shack is a small, simply-built house. Shacks are often seen near the beach or in the wilderness.
Another word for shack is hut.
A sign is something that conveys some kind of meaning. Signs might be made up of pictures, words, or a combination of both. Many signs are just symbols, so that people will recognize what they mean no matter what language they speak. Signs don't need to be painted on a board - for example, deaf people communicate with sign language, using their hands to make symbols.
A silo is a large cylindrical structure for storing a large amount of something. Silos are most often seen near farms for storing grain, but can also be used to store coal, wood chips or even missiles.
A spire is a tall, pointed structure usually found as a type of roof on the tallest part of a grand building. Spires are common on churches and cathedrals.