Like the Kentile Floors sign before them, the Ferrara Brothers' concrete conveyor belts—familiar to F/G riders trundling through Smith-9th Street—are not long for the Brooklyn skyline. A year after the plant began operations in 1973 on the banks of the Gowanus, the city seized the property under eminent domain, making the company its long-term tenant. Now, this industrial hold-out’s time has come: in the last few weeks, the facility has been reduced to a sea of scrap, a jungle gym of steel shards.

The Ferrara Brothers are opening a new plant in Sunset Park. Their old space, which supplied concrete for the 9/11 Memorial and the Second Avenue subway, is fated for residential development, reportedly part of the Gowanus Green, a public-private project in the works by an assortment of developers including the city and Hudson Companies.

In the meantime, some 50 of us descended upon it after dark, sneaking onto the property for a beach party on a cool summer Friday. A member of the urban explorer group LTV Squad and I scattered plastic beach toys among the rusted tools on an inclined plane of sand along the edge of the Gowanus. From the seemingly untouched security booth—still full of safety vests, radio equipment, clock-in cards and a customized mousepad—we motioned guests towards our encampment. The lot being wide open at a dead end, some cars accidentally drove into it that night, but all realized their mistake before winding up in the canal.

Our candles glowed inside the largest remaining structure, a four-or-so story hulk full of twisted, grated stairs so the fire’s warm glow was visible from all angles through the slats. People packed a third-floor balcony open to the elements on all sides, its end caution-taped off. Using a bucket of tar we found on another balcony, we painted the walls. A production assistant of sorts clambered onto the roof to cast a light for a swimsuit photo shoot going on in a stagnant puddle of fetid water between the scrap mountains below us.

Out on the beach, hot dogs cooked on the grill, which leaned against an overturned silo that, by the end of the night, had been carpeted in glow sticks. Bay Ridge native Joseph Loonam did a stand-up set for an audience sprawled on blankets and perched on the jagged edges of former manufacturing equipment. A beach ball was rolled down the conveyor belt to many shouts and cheers. A chain became a zipline of sorts, a metal bungee cord to swing across a deep green pool between the main building and one of the larger scrap heaps.

Well into the morning, we wandered away from the site, leaving behind our sandcastles, only slightly more ephemeral than this small city of steel, once a hub of concrete creation and one of the Gowanus’ final industrial stragglers, soon to be a memory along its shores.

Hannah Frishberg is a fourth-generation Brooklynite and freelance reporter. She was previously the Editor in Chief of Brokelyn. Her work has appeared in the New York Post, CityLab, the Columbia Journalism Review and elsewhere. Follow her on Twitter: @hfrishberg