The cheapest way to get around New York is on foot but a quicker way is the Subway. Many years ago it had a bad reputation but nowadays it’s clean and quick.
We were in New York for 11 days, so we bought the 7 day pass for $30, as the single fare is $2.50 the ticket paid for its self after 10 journeys. It is such good value that after the seven days we renewed our metro ticket for another seven days. We used the subway so much it paid for itself again.
In most of subway stations there is some mosaic art.