If you have to ask, you should use the door marked "Morlock"

From Business Insider:

An NYC High Rise Is Putting In Separate Entrances For Rich And Poor Renters

A luxury high-rise apartment in Manhattan’s Upper West Side is set to have a so-called “poor door” — a separate entrance for low-income residents receiving subsidized housing.

The 33-story building — 40 Riverside Boulevard – being developed by Extell Development Company will have 219 condominiums selling for more than $1 million each.

But by including 55 affordable housing units on the first few floors renting at a starting price of $845 a month, the developer could get a tax break, according to the West Side Rag.

With this disparity between the million-dollar condos for purchase versus the units for rent at a phenomenally low price for Manhattan, the developer decided to design the building with separate entrances for those who own condos and those who rent at a price below market value. As one might expect, this “rich door,” “poor door” situation doesn’t sit well with some.