A small enclave in the northern reaches of the Upper East Side, Carnegie Hill is in many ways unlike any other neighborhood in New York City. Next to Central Park, quiet streets full of limestone rowhouses and pre-war co-ops are home to some of Manhattan’s most powerful residents, all of whom desire to claim this historic section of the Upper East Side as theirs. Yet Carnegie Hill wasn’t always like this; until Andrew Carnegie built his now-landmarked mansion on Fifth Avenue and 91st Street in 1901, much of the area was farmland. In turn, wealthy New Yorkers built their estates in the surrounding blocks, in doing so creating one of Manhattan’s most architecturally-significant neighborhoods. With the arrival of the subway a decade later, Carnegie Hill’s expansion continued at an even more rapid pace.