Today I walked down Lexington Avenue, about 8 miles.
Lexington Avenue is the analog to Madison Avenue, running north/south from 131st St. to 21st St. a half block east of Park Avenue. Like Madison Avenue, Lexington Avenue was created by real estate developer Samuel Ruggles in 1832 as part of a plan to increase the value of the land that would become Gramercy Park and Union Square (two of his projects).
Lexington Avenue terminates at 21st St. at Gramercy Park, one of only two private parks in the City. Membership in Gramercy Park is restricted to residents of the surrounding buildings, who pay an annual fee of $7,500 to receive a key to the park - around 400 people currently have keys. In the center of the park is a statue of the famous 19th-century Shakespearean actor Edwin Booth, who today is better known for his relationship to his younger brother, John Wilkes. (John was also a famous actor - it would be like if Casey Affleck shot the President today.)
Below Gramercy Park, the street becomes Irving Place (named for Ruggles' friend Washington Irving) through to 14th St. Below that I picked up Lafayette / Centre St. through SoHo down to City Hall Park. New York's City Hall was built in 1811 and is the oldest city hall in the country still in use.