One entrance for the rich, and one for everyone else.

A building going up on New York’s posh Riverside Boulevard has been built with this exact philosophy. One Riverside Park, a new 33-story luxury condominium building with apartment prices ranging from $1.9 million to more than $25 million, is one of a handful of buildings taking advantage of a Bloomberg-era change to the city’s zoning law, allowing the developer Extell to essentially put a wall between its wealthy owners and those living in the building’s affordable housing units.

An impassable concrete wall down the middle of the building will separate 55 lower-priced apartments, designated for low-income tenants, from the building’s remaining 164 units. By designating roughly 20 percent of the building’s space as affordable, Extell was able to secure lucrative tax credits and the right to build a taller building than would typically be permitted.

The city approved the controversial application this week, according to the New York Post.

Extell declined to comment.

According to a spokesperson in the mayor’s office, the city’s zoning laws were changed in 2005 under former New York City Mayor Michael Bloomberg. The change was implemented in 2009. It allows for developers to reap the benefits of building affordable units in their new developments, while at the same time allowing them to segregate those with less means to one area of the building, so long as the affordable housing is “on-site or off-site within the same community district.”

According to the spokesperson, the building was already well under construction when Bill de Blasio and his team took office, and it would have been too costly to stop, because it would have meant suing the developer and reconstructing the building.

At that point, the mayor’s office told Al Jazeera, it came down to fighting costly litigation or giving families on the affordable housing wait-list access to a place to live. The spokesperson also said there are likely to be “a few more” buildings like this between now and next year, when the de Blasio administration plans to overhaul the zoning laws to prevent this sort of segregation.

Tenants in the affordable units will enter through a door located in the “back alley” of the building, and their units will face the street, while the luxury condos on the other side will face out onto the Hudson River and park across the road.

Similar impositions have been placed on lower-income residents in other luxury buildings throughout the city.

One Northside Piers, one of two towers going up in Williamsburg, will have a “poor door” and be separate from the neighboring tower by the same builder. At another building at 34 North 7th Street, less-wealthy tenants will not have access to the building amenities, according to real estate news website The Real Deal.

At the time of Extell’s application in 2013, David Von Spreckelsen, senior vice president at Toll Brothers — the developer of One Northside Piers — told The Real Deal he didn’t see what the issue was with having separate entrances.

“No one ever said that the goal was full integration of these populations,” Von Spreckelsen said.

“So now you have politicians talking about that, saying how horrible those back doors are. I think it’s unfair to expect very high-income homeowners who paid a fortune to live in their building to have to be in the same boat as low-income renters, who are very fortunate to live in a new building in a great neighborhood.”

Manhattan Borough President Gale Brewer has vowed to reject all future developments that have separate entrances.