The park — a memorial to Franklin Delano Roosevelt — was conceived four decades ago. The visionary architect who designed it died in 1974. The site, a landfill along one of the more dramatic stretches of waterfront in New York City, remained a rubble heap while the project was left for dead.

But in a city proud of its own impatience, perseverance sometimes pays off. Next month, on that triangular plot on the southern end of Roosevelt Island, the four-acre Franklin D. Roosevelt Four Freedoms Park will open, a belated and monumental triumph for New York and for everyone who cares about architecture and public space.

Louis Kahn is the architect. He completed drawings for the park just before he died suddenly, in Pennsylvania Station, at 73. That Kahn’s plan survived periodic calls to privatize the government-owned property and build a hotel and fancy town houses, among other commercial proposals, proves the benefit of resisting short-term financial imperatives. In the end the value of the project goes far beyond dollars and cents.

It gives New York nothing less than a new spiritual heart. That’s to say it creates an exalted, austere public space, at once like the prow of a ship and a retreat for meditation. It’s a memorial, perhaps naïvely optimistic but uplifting and confident, unlike the one at ground zero. It is as solemn as the Roosevelt wartime speech it honors, a call to safeguard the freedoms of speech and worship and the freedoms from want and fear. From inside the great, open granite enclosure that Kahn called the “room” at the tip of the island, a long fly ball away from the United Nations, a visitor looks out over the city and the churning waters of the East River in the direction of the Statue of Liberty, the ocean and Europe. It is the long view that Roosevelt had for America.