An extraordinary domed quadruplex at the landmarked Police Building in Little Italy has sold for just $10 million — one quarter of its original $40 million asking price.

The unique residence, which comes with its own secret room hidden behind a clock tower, is just the latest example of Gotham’s wacky real estate market where a bevy of trophy apartments are selling — but at rock bottom prices.

The seller was Ahmass Fakahany, former global president and COO of Merrill Lynch, and his wife Alsun Keogh.

Fakahany is currently head of the Altamarea restaurant group, whose holdings include the high-end Marea on Central Park South.

The penthouse at 240 Centre St. was once owned by fashion designer Calvin Klein and also by tennis player Steffi Graff. The sale was first reported by the Real Deal.

The new buyer is Aaron Chaus, CEO & founder of Clear River Investments, a private equity group focused on the fast food restaurant industry. The listing brokers are Tal and Oren Alexander of Douglas Elliman and Adam Modlin of the Modlin Group.

It’s just the latest trophy pad that has sold for a fraction of its original asking price. A stunning spread at the Plaza Hotel owned by fashion billionaire Jurgen Friedrich and his wife Anke Beck-Friedrich is also in contract for around $20 million — after being on and off the market for 13 years, as Gimme recently reported. (They had bought the unit, known as the Astor Suite, foe $25.49 million and tried to flip it the following year for $55 million.) 

This downtown building served as the NYPD’s headquarters from 1909 to 1973, and converted to luxury coops in 1988.

The sprawling 5,500-square-foot penthouse, spread out over four stories, features four bedrooms, a striking spiral staircase, internal elevator and a clocktower room, which once housed the clock’s mechanics. The third floor, which showcases the dome room, with Palladian windows and high ceilings. 

If that’s not enough to brag about, there’s also panoramic city views, two garden patios and two terraces.