City of Brick and Steel is a guide to the hidden structure that keeps over a million buildings in New York City buildings standing. We explain the basics of structure within the main types of buildings that make up the city as it is today. We also include descriptions of common types of damage and how to identify the different types from visible clues. The buildings date from the mid-1600s to the present and cover structure ranging from carpentry by farmers building their own houses to record-breaking steel and concrete high rises. The well-known skyscrapers and brownstones are examples of a broad spectrum of building types, each with its own particular structure, its own history of use, and its own patterns of aging.