Prudential Center landlord Boston Properties plans to spend over $125 million to create a new attraction on the top of the Back Bay landmark.

Both the existing Skywalk Observatory and the Top of the Hub restaurant will close April 18 to make way for the redevelopment. Select Restaurants said this month that Boston Properties declined to renew its lease for the Top of the Hub.

During a conference call today to discuss fourth quarter earnings, Boston Properties President Douglas Linde said the company plans “an extraordinary experience” for local residents and tourists, spanning the 50th through 52nd floors of the building, which is Boston’s second-tallest. Completion is scheduled for mid-2022, he said.

The Top of the Hub has operated for 53 years, and Select Restaurants also operates the observatory space.

Boston Properties also is in discussions with a potential anchor tenant for 171 Dartmouth St., the office tower component of its 1.3 million-square-foot Back Bay station redevelopment, but does not have a signed letter of intent yet, Linde said.

Boston Properties’ 165 Dartmouth St. garage will be partially demolished to make room for a 26-story, 668,000-square-foot office tower at Dartmouth and Stuart streets.

Boston Properties on Tuesday reported revenues grew 7 percent to $757.5 million during the fourth quarter ending Dec. 31. Funds from operations rose 18 percent to $289.9 million.