About 7 miles and 5 hours.
We'll start at the Time Warner Center at Columbus Circle and walk across Central Park to The Frick Collection to see Cagnacci’s “Repentant Magdalene” on its last day of exhibit and other exhibits. (Admission to the Frick is pay what you wish on Sundays from 11:00 a.m. to 1:00 p.m.)
Here is a link to the Frick: The Frick Collection.
After an hour in the Frick, we'll walk back across Central Park and spend about 45 minutes having lunch at the Whole Foods at 97th Street and Columbus Avenue.
Next, we will walk west on 97th Street to Riverside Drive and north on Riverside Drive to 116th Street for a walk across the Columbia University campus to view some sculptures, particularly Scholars Lion by Greg Wyatt, then to St. John the Divine Cathedral at Amsterdam Avenue, where Wyatt's Peace Fountain is located. (Admission to the Cathedral is pay what you wish, but please pay something, they get snippy.)
Greg Wyatt grew up in Rockland County, studied at Columbia and the National Academy of Design, and is Sculptor in Residence at the cathedral. Here is his Wikipedia bio: Greg Wyatt
We should be done at the Cathedral by 3:30, though you can linger as long you wish. The 1 train is nearby at 110th Street and Broadway, the C train is nearby at 110th Street and Central Park West.
Meet: 10:30 a.m. inside the Time Warner Atrium at Columbus Circle, Take the 1, A, D or C train to 59th Street/Columbus Circle.