Construction crews placed the final beam atop the 60th story of the Millennium Tower in Boston’s Downtown Crossing on the two-year anniversary of its groundbreaking.

The 442-unit luxury tower has pre-sold 90 percent of its units in advance of its anticipated summer 2016 opening.

Richard Baumert, a partner with developer Millennium Partners, said the strong demand reflects the property’s distinctive luxury amenities including a restaurant by James Beard award-winning chef Michael Mina and Pabu, an informal Japanese lounge by sushi chef Ken Tominaga located on the first and second floors. The complex will contain the city’s largest resident fitness center at 10,000 square feet.

“We’ve learned over the last 15 years that our residents want a building that has amenities,” Baumert said. “The validation has been that we’ve sold 90 percent in less than 11 months. It’s quite extraordinary.”

Total sales exceed $800 million.

The remaining units are listed starting at $2.9 million. The 12,846-square-foot penthouse that spans the entire top floor is still available for $37.5 million and has attracted substantial interest, Baumert said.