Joseph Sitt’s Thor Equities LLC agreed to sell land on Manhattan’s Fifth Avenue for $275 million, almost double the price the firm paid for the property in 2011, according to two people with knowledge of the agreement.

Ceruzzi Properties LLC, a Fairfield, Connecticut-based real estate investor, is under contract to buy the 300,000-square- foot (27,900-square-meter) site at 520 Fifth Ave., said the people, who asked not to be identified because the deal is private.

Sitt declined to comment. A representative for Ceruzzi, whose New York holdings include the Upper East Side building that was home to Elaine’s restaurant, didn’t immediately respond to requests seeking comment.

The site, between 43rd and 44th streets, was left vacant when Sitt demolished two pre-war buildings acquired in 2011 for $150 million. In December, the developer filed plans with the city to build a 71-story retail, hotel and residential glass tower. The new owners intend to go forward with Thor’s design, said one of the people with knowledge of the agreement.

Land values in New York City are surging, enabling owners such as Thor to capitalize on relatively recent acquisitions. A wave of foreign investors seeking a haven is helping push up prices. One of Ceruzzi’s partners on the Fifth Avenue project is a Chinese firm, the people said.