Here's some info on "Manhattanhenge"...http://www.haydenplanetarium.org/resources/starstruck/manhattanhenge/
Sunset looking down 34th Street. One of two days when the sunset is exactly aligned with the grid of streets in Manhattan
by Neil deGrasse Tyson, © 2001-2009
What will future civilizations think of Manhattan Island when they dig it up and find a carefully laid out network of streets and avenues? Surely the grid would be presumed to have astronomical significance, just as we have found for the pre-historic circle of large vertical rocks known as Stonehenge, in the Salisbury Plain of England. For Stonehenge, the special day is the summer solstice, when the Sun rose in perfect alignment with several of the stones, signaling the change of season.
For Manhattan, a place where evening matters more than morning, that special day comes on Saturday, May 30th this year, one of only two occasions when the Sun sets in exact alignment with the Manhattan grid, fully illuminating every single cross-street for the last fifteen minutes of daylight. The other day is Sunday, July 12th. These two days give you a photogenic view with half the Sun above and half the Sun below the horizon—on the grid. The day after May 30th (Sunday, May 31), and the day before July 12 (Saturday, July 11) will also give you Manhattanhenge moments, but instead you will see the entire ball of the Sun on the horizon—on the grid. My personal preference is the half-Sun.