A fire in Manhattan, New York, destroyed 345 buildings, killed 30 people, and caused at least $5 million in damage.

The Great New York City Fire of 1845 broke out on July 19, 1845, in Lower Manhattan, New York City. The fire started in a whale oil and candle manufacturing establishment and quickly spread to other wooden structures. It reached a warehouse on Broad Street where combustible saltpeter was stored and caused a massive explosion that spread the fire even farther.

Manhattan is the most densely populated and geographically smallest of the five boroughs of New York City. Coextensive with New York County, Manhattan is the smallest county by area in the U.S. state of New York. Located almost entirely on Manhattan Island near the southern tip of the state, Manhattan constitutes the center of the Northeast megalopolis and the urban core of the New York metropolitan area. Manhattan serves as New York City's economic and administrative center and has been described as the cultural, financial, media, and entertainment capital of the world.