Yes there were and still are tunnels under the city. Several entrances still exist but most are on private land. The entrances on public land are kept secret as the tunnels often connect to the basements of home owners nearby.
There really is no "old city" in New York, unlike a lot of places. New York City has a tendency to tear down the old and build on top of it, therefore, there's not much old stuff left. There are plenty of underground tunnels, but most of them are filled with trains and utility pipes. Most abandoned tunnels are not accessible, and there are very few at that. I know there are lots of myths about abandoned tunnels that run all over New York City, but in most cases they are simply not true. As a point of fact, New York is covered with buildings - the construction of these buildings' basement would have destroyed most of the old tunnels years ago. For a fun read, you might check out "The Mole People," a book about the people that are supposedly living in the few tunnels left that were/are still accessible (illegally).
Many of New York City's homeless live in the abandoned subway tunnels, especially during the winter months.
The most popular city in he US is New York City.
It is the 4th largest US City by population.
in the tunnels below goldenrod city
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Philadelphia was the capital city of the US during most of the Revolutionary War.
New York City has the highest population in the United States.
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Large tunnels in cakes can be prevented by shaking the pan before you bake it to take out most of the air bubbles causing those tunnels.
Most popular us city is New York City