7. Mitchel Square in Washington Heights

If you don’t want to go all the way into one of the city’s parks, you can find Manhattan schist in a pocket park in Washington Heights at Mitchel Square, named in honor of Mayor John Puroy Mitchel, known as the Boy Mayor. He was elected to office at age 34, the second youngest in New York City history but died a tragic death just short of his 39th birthday in a military aircraft training accident.