At nearly three-quarters of an acre, the park is to have a tot lot and a grove of trees but mostly lawn, a rare sight downtown. The park must have public restrooms – another rarity – and a small coffee shop or restaurant at the corner of East Island and 14th streets, which officials said would be "eyes on the park" for security.

Details of landscape architect Marty Poirier's design are to be completed after two more public workshops. The deal must also be approved by the City Council.

The board of the Centre City Development Corp., the downtown redevelopment agency, has approved a contract with Pinnacle International, which plans to build two towers for 619 condominiums with 800 off-street parking spaces and two smaller buildings for townhouses and street-level shops.

The agreement, reached May 26, obliges the developer, Pinnacle chief executive Michael De Cotiis, to construct and maintain the park in perpetuity. It gives him three years to show CCDC proof that the park and his project are progressing.

The city gets the park at no cost, even if Pinnacle's tower projects are stalled.

The blocks between 14th and 15th streets are so-called superblocks because they are twice the size of typical downtown blocks. The city owns one-quarter the block, which sits above an earthquake fault and cannot be developed. The block has warehouses on it.

De Cotiis will pay the city $5 million for the city's property, though it is forever restricted to park uses. But the development rights to the parkland and airspace above it have been transferred to the two towers, of 31 stories and 39 stories, on 15th Street.

The park is a welcome change for this block, said Brenda Kayzar, president of the the East Village Community Action Network, a neighborhood group.

The agreement is "a really innovative way to get public spaces and a public good in an area that's been overlooked," she said.