New York City is perpetually starved for space for new residential and commercial developments. But one proposed undertaking would yield an additional 400 to 800 acres: filling in the Harlem River.

So goes the proposal of Charles Urstadt, former New York state housing commissioner and namesake of 1971’s Urstadt Law, which handed Gotham’s power to pass local rent laws to the state legislature. In a recent article on Crain’s New York, Urstadt argued that plugging the Harlem River would not mean foregoing a natural waterway, as the Manhattan/Bronx dividing line was crafted as a man-made shortcut between the Hudson River and the Long Island Sound in 1904.

Filling in the seven-mile-long river, which stretches 400 feet wide on average, would create a space between four and eight times the size of Battery Park City. “Planners would have a free hand to dream big about the kinds of development New York needs most,”Urstadt opined.

Among the former housing commissioners ideas are expanding Columbia and New York University’s respective campuses to the area, or drawing schools like Stanford or MIT as Cornell came to Roosevelt Island. Housing accessed by light rail is another of his suggestions, as is the addition of a park.

According to Urstadt, “Because the land itself would be owned by the city, then rented (most likely for 99 years) to developers, the income stream would help pay for schools, parks and other amenities. Moreover, as land values (and the ground rents they command) rise over time, this project would generate surplus income for the city treasury.”