Below, you can see the neighborhood of Marble Hill just across the river from the northern tip of Manhattan. A lot of people ask if I included this neighborhood in my walk. Marble Hill used to be part of Manhattan island; notice how the streets still curve to follow the original shoreline. In the early 19th century, a canal was dug just south of present day 225th Street, and Marble Hill itself became in island- cut off from the rest of Manhattan. Later, the original river to the north was filled in, and the neighborhood became part of the U.S. mainland- but it always remained part of the borough of Manhattan. I arbitrarily decided that my walk would just encompass the current island of Manhattan. Other outlying parts of the borough include Ellis, Liberty, Governors and Roosevelt Islands.