In Manhattan, the avenues generally run north-south, and the numbered streets generally run east-west. So 5th Avenue runs north-south, for example, and 53rd Street runs East-West.
There are two days every year when the sun sets exactly on the line of the east-west numbered streets. Those days are called either the Manhattan Solstice, or the Manhattan henge.
During the last 15 minutes on those two days, the cross-town streets are fully illuminated, from the East River to the Hudson River, as the sun appears to set exactly in the middle, at the end of each of those streets. The two days are May 28 and July 12. It's quite spectacular. Much like the city in which it occurs.