Philippine settlements are classifiable as cities, towns, and villages. While the national capital, Manila, stands alone, chartered cities form the second-highest level of urban organization. Small cities and large towns are often interchangeable. Both are based on the number of villages included under their jurisdiction. In Christian areas a Catholic church identifies the town. In Sulu a mosque marks a specific ethnic neighborhood or a village. Typically, Samal villages are of the strip kind, with houses built on stilts along the coastal lines. Denser villages are built out further into the sea and are accessible by platforms serving as passageways. Samal mosques, schoolhouses, and health dispensaries are built inland, as are the homes of more affluent and acculturated families. A typical house has two sections: one part roofed, the other not. Most household chores are done in the latter, while formal activities and sleeping take place in the former. The traditional thatched roofs and walls have given way to more durable materials such as galvanized iron, lumber, and concrete.