One of my favorite architectural features in New York, or indeed anywhere, is a group of three rats crawling up lines into Grand Central Station. I noticed them decades ago and have often asked friends from the City if they've seen them. Most have not, even people who have walked by this portion of Lexington Avenue hundreds of times.
What's the background? Here's a 1995 explanation from the New York Times:
A Rat Revealed
Q. Why is there a sculpture of a rat crawling up one of three wires that holds the awning over the Graybar Building entrance to Grand Central Terminal on Lexington Avenue?
A. Good eye. That rat (above) is not easy to spot. The architects of the Graybar building, Sloan & Robertson, included three cast-iron Norway rats in the design for the building. The sculptures depict sharp conical baffles on the mooring lines of ships, which were intended to discourage rats from climbing aboard. One of the three rats was stolen, and the other is being used to fashion a replacement, said Patricia Raley of Metro-North Railroad, which manages the terminal.
1110 NYC adds:
The art deco Graybar Electric building was built in the 1920s, and as Graybar was originally a steamship company, the architects designed it with a maritime theme. Hence the mooring lines (the awning poles) of a ship securing the building to Lexington Avenue complete with its anti-rat funnels that deterred rats from stowing away on ships. This building has its own three evil cast iron rats climbing above the building’s entrance.
Apparently as the years went by, one of the rats mysteriously disappeared. But in 2000, when the building was being restored, there were special instructions to “replace the missing rat”.
Even more unusual and not so obvious are the rosettes that connect the poles are actually decorated with rat heads.