The developer who built the tallest residential building in the Western Hemisphere (for now) has submitted plans for a massive office tower across from St. Patrick’s Cathedral, which he hopes will reshape the city’s skyline.

Macklowe Properties has assembled a mid-block plot between East 51st and 52nd streets for what he is calling “Tower Fifth,” which, at 1,551 feet, it would be the second-tallest in both New York City and the entire Western Hemisphere. Macklowe Properties founder Harry Macklowe filed preliminary plans with the Department of City Planning Friday, The New York Times reports.

“It’s a chance to change the skyline,” Macklowe told the Times. “Tall buildings are a reality … The days of restrictions on buildings are really over. This is a building that’s never been built before, a 21st-century building.” The proposed building will be 216 feet taller than One World Trade Center, though that building will hold its title as the tallest in the city because of its mast, which gives it an official height of 1,776 feet. Tower Fifth would be 12 inches taller than Extell Development’s luxury project Central Park Tower, which is currently under construction.

Macklowe is planning on acquiring a large portion of air rights from St. Patrick’s Cathedral, Crain’s New York Business reported last week.

The building would feature “unusual elements” according to the publication, citing people who have seen the plans. It would have a tapered midsection and an observatory on the top floors. The mass-damper in the building, a device that reduces sway in skyscrapers, would be on display with a seismograph. Macklowe also plans to include a 60-foot, glass-bottomed slide in the observation deck, similar to the popular attraction the Skyslide at U.S. Bank Tower in Los Angeles.

Macklowe has reportedly been gathering sites for the building for the last two years, and there are five parcels he wants to acquire. The 82-year-old developer most recently built the 1,379-foot 432 Park Ave. Last year, he closed on a $750M construction loan for his billion-dollar office-to-residential conversion at One Wall Street. His public divorce proceedings were also finalized last year, with a Manhattan Supreme Court Justice splitting the $2B fortune he shared with his ex-wife Linda evenly between the two. The tabloid-fodder ordeal lasted two years.

UPDATE, JAN. 22, 7 P.M. ET: This story has been updated to reflect preliminary plans have been filed with the city.