The case of a mysteriously vanished black marble bench—which has since reappeared—in the pedestrian atrium of Trump Tower may lead the city to hold landlords more accountable for privately owned public spaces, or POPS.

The Wall Street Journal reports that on Wednesday, three new bills to protect POPS were introduced in the City Council, sponsored by Council members Ben Kallos and Daniel Garodnick. The first of the three bills would raise penalties for building owners from $4,000 to $10,000 for first offenses, and to $20,000 for additional offenses. Under the bill, a fine of up to $2,500 could be imposed for each month a violation goes unattended.

The second bill would hold landlords accountable for their promises by requiring new signs to appear in the spaces that explain what amenities should be available to the public under the agreement. The signs would also tell people how they can register complaints if the POPS aren’t delivering on their promises. The third bill would be responsible for creating a website where complaints can be registered. Under the third bill, POPS would undergo annual inspections.

POPS, as they’re known, are often used as a bargaining chip for developers looking to build larger. In exchange, they dedicate a portion of their property to the city for use as public space. Trump Tower is just one example: When it was being built, part of the atrium and two outdoor landscaped terraces were designated as POPS. In exchange, the city granted Trump the right to add an additional 20 stories to the building.

When an area becomes a POPS, the city must approve any changes to the area. (The Trump Tower bench disappeared without approval from the city in the early aughts. It returned in July 2016 after a New York Times report.) Continued reports of unregistered changes and negligence, at Trump Tower and other POPS throughout NYC, cited by the Wall Street Journal have put the city on guard.

The Wall Street Journal notes that 538 POPS throughout the city provide about 3.5 million square feet of public space, roughly equivalent to about 10 percent of Central Park. In exchange, landlords have been given the right to build an additional 23 million square feet, or more space than about eight Empire State Buildings.