Until yesterday I had never heard of this but according to Space.com the sun will set tonight in exact alignment with the cross streets of Manhattan's street grid,
This is apparently known as Manhattanhenge.34th Street and 42nd Street are good viewing locations and the ball of the sun will be half above the horizon (Tomorrow, the whole sphere will be above the horizon at 817pm), half below. There is another opportunity to see the alignment at 825pm EDT on 11 (whole sphere) and12 July (half sphere)
Manhattan's street grid was laid down by the Commissioners' Plan of 1811, which was adopted by the New York State Legislature. New York isn't the only city that can have its own "henge" events: Any city crossed by a rectangular grid has days where the setting Sun aligns with the streets. But a clear view of the horizon and straight streets are needed, and New York might be the only city that fits the bill.
I'll, probably never get that chance to see the winter solstice sunrise light up the passage grave in Newgrange but this looks like something worth seeing one day.