radical - an atom or group of atoms with at least one unpaired electron; in the body it is usually an oxygen molecule that has lost an electron and will stabilize itself by stealing an electron from a nearby molecule; in the body free radicals are high-energy particles that ricochet wildly and damage cells.
The Metropolitan Museum of Art, colloquially the Met, located in New York City, is the largest art museum in the United States and among the most visited art museums in the world. Its permanent collection contains more than two million works, divided among seventeen curatorial departments.
The Flatiron Building is the triangular building at right center. To the left is the Met Life Tower, with Madison Square Park in the center. Madison Avenue begins at 23rd Street between the park and the tower, and runs uptown (toward bottom of image).