Tabby is a type of building material similar to concrete, but made from crushed shells, lime, sand, and water. This is what built colonial fortifications, plantations, and other buildings along the northern coastline of Florida. Thomson Tabby House is one of these - although they are called ruins, the house never was completed. In 1854, Charles Thomson started his tabby home but construction ceased when he passed away in 1855. Today, the ruins of the half-constructed home are what remain.