They built roads and property in an ad-hoc way to accommodate the terrain. It was known as the 'Island of Hills' by those initial landowners who settled in the city. The landscape of New York in those early years was rough and rich, home to hills and valleys, streams and ponds, forests and swamps.
It even served briefly as the capital of the USA from 1785 until 1790. The city's advantageous position at the mouth of the Hudson River, which feeds onto the Atlantic, helped it grow as a significant trading port and it by 1890 it was the largest city in the USA, and has been ever since. In 1664 the city came under British control and was renamed New York after King Charles II of England. New York was first 'officially' discovered in 1626 by Dutch colonists, and originally named New Amsterdam. What was New York like before the grid plan?
You either love it or hate it, but nothing says New York like the street grid of Manhattan.