Jacob Wrey Mould did remarkable decorative work in Central Park, at Bethesda Terrace and elsewhere. You can also see his hand in the oldest section of the Metropolitan Museum. These stairs – which are, yes, one of my favorite things in the MMA – are from Wing A, opened to the public in 1880.
In the floor plan below, these stairs are one of the sets at the left side (toward Fifth Avenue). The original building consisted mostly of the vaulted room where the Met’s Christmas tree stands.
And here it is from the outside. The main entrance, facing Fifth Avenue, is that wee wooden staircase toward the right.
I’ve described the evolution of the Metropolitan Museum of Art’s building, with contemporary photos and architectural drawings, in an essay on the Forgotten Delights site. Reading it will give you a whole new perspective on the Met – and some understanding of why it’s so confusing to get from one part to another.