The final part of this three-part series exploring what it is like to live in America's biggest and busiest city. Anita Rani, Ade Adepitan, Ant Anstead and Dan Snow are in New York. From their base in Central Park, they reveal the hidden systems and organizational miracles that keep the world's busiest urban park clean and green. They meet the behind-the-scenes team who look after all 843 acres. Ade heads to Harlem and meets residents who are benefiting and suffering at the hands of gentrification. The price of a townhouse there has gone from $50,000 to over $4 million in 30 years. Ant is at Hudson Yards on the west side of Manhattan, where an entirely new district is being built on top of a functioning rail depot. It is an innovative building solution to the island's lack of land. Dan Snow is at Coney Island discovering that television, air conditioning and extreme weather almost killed off this historic amusement zone. And we head to a multi-million-dollar penthouse apartment in the company of estate agent Paula Del Nunzio, who holds the record for selling New York's most expensive house: a cool $53 million investment.