Last night, the Empire State Building lit up in the New York State's flag colors of orange, white, and blue to celebrate the 50th anniversary of the NYC Landmarks Law. The law was put into place after the destruction of the former Penn Station as a means to assure people that historic structures and significant landmarks pertaining to NYC history don't disappear just because somebody comes around with a handful of money.
Over the last 50 years, the NYC Landmarks Law has defined entire neighborhoods and saved precious buildings from demolition and destruction (or alteration from its original form). It is just one of the ways NYC preserves its history when so much else is changing in the city. See this map here for all the places saved over the years.