The design was inspired by English row homes, and they generally include an open living area, at least two bedrooms, and are two floors tall. The property is thin and lengthy in form. Almost every Charleston single house has its own patio with an entrance facing the street. These entries are often called "dog doors" because they were designed to be opened by large dogs who would be able to enter but could also go outside if they wanted to. The most distinctive feature of a Charleston house is probably its front door which is usually made of wood with heavy metal hinges and has several locks on it. This door is one of the ways that slaves entered their owners' homes during the period of slavery. They would ring the bell or knock on the door and say something like "Alfred pay my master his cut from last year's crop." Or they would just show up! If the owner wasn't home, they would take what they wanted and go. Slaves had no legal right to enter their owners' houses so this was a way for them to get access. After slavery, the door became a way for family members to communicate without having to go through servants. The patriarch of a family would sit in his chair on the porch and ring a little bell when he needed someone to bring him a cup of coffee.