The skylight at the World Trade Center’s $4B Oculus is leaking

The skylight that crowns the spiky, $3.9 billion World Trade Center Oculus has sprung a leak.

A rubber seal that runs along the spine of the retractable skyline is believed to have ripped during its opening and closing on the 2018 anniversary of the 9/11 attacks, The Wall Street Journal reports.

Some $30,000 by The Port Authority of New York and New Jersey was spent this winter to repair the tear using black strips of Flex Tape, but the skylight at the massive transportation hub and shopping mall leaked again on May 5, the newspaper reports. The new leak has forced the Port Authority to place barriers and signs warning of the slippery marble floors on the center’s cavernous concourse.

The Santiago Calatrava-designed Oculus opened its doors on March 3, 2016 to praise and controversy for the spiny sculpture that tops it. Made up of 224 panes of glass, the skyline is arranged in 40 panels that are powered by motors and are must more seamlessly in synch for the structure to open and close.

The Oculus was built at an angle so that, when open, the skyline would capture the sun’s rays each morning on the anniversary of 9/11—during the exact time that aircraft struck the World Trade Center’s towers in 2001.

Since then it has suffered a series of mishaps. In 2017, a malfunctioning elevator injured two, and the Port Authority pointed to construction work as the cause of a ceiling leak at the eastern end of the hub near Fulton Center.

The Port Authority plans to replace the skylight’s rubber seal this summer, ahead of this year’s 9/11 anniversary, according to The Wall Street Journal. It is unclear how much those repairs will cost.

The Port Authority did not immediately return Curbed’s request for comment.