The Top of the Hub restaurant and Skywalk Observatory at the top of Boston’s Prudential Center tower will close April 18 to make way for what landlord Boston Properties calls an “exciting” new tourist attraction.

This year would have been the iconic Top of the Hub’s 54th year in operation and has been the site of countless family celebrations, business deals, celebrity meals and marriage proposals. Together, both venues employ more than 200 people. Select Restaurants, which operates both the 52nd-floor restaurant and 50th-floor observatory, said in a statement that employees learned of the closures from managers this afternoon. Both venues will continue to operate up until their closing date, the company said.

Select Restaurants said in a statement that Boston Properties declined to renew their lease. The lease expires in May, a Boston Properties spokesperson said.

“Despite continued sales growth, a commitment to once again invest millions of dollars in the restaurant, and our heartfelt desire to operate the restaurant as we have for decades, Boston Properties chose not to extend our lease,” Select Restaurants Chairman John Quagliata said in a statement.

In a statement, Boston Properties Executive Vice President Bryan Koop thanked Select Restaurants for the company’s long run in the Prudential building.

“Boston Properties is planning an exciting new design for an observatory at Prudential Center that will provide a world-class visitor experience for visitors to Boston. We thank the community in advance for their patience during the construction process and look forward to sharing plans for this exciting new experience,” Koop said.

Boston Properties also owns 200 Clarendon a few blocks away. The ex-John Hancock tower’s own observation deck has been closed to the public since Sept. 11, 2001, initially due to security concerns, but was later converted to office space by the building’s prior owner.