A North Shore parking operator is offering the city's Stadium Authority $13 million for two parcels of land on the North Shore, in part to build a "signature office tower" between Heinz Field and PNC Park.

The parcels in question are reserved for Columbus-based Continental Real Estate Cos. for development as part of an option agreement reached with the Pirates and the Steelers nearly a decade ago.

However, Merrill Stabile, general partner of 501 Martindale Associates and president of Alco Parking, said he is willing to offer the Stadium Authority far more for the land than the prices set in the option agreement, which he said is set to expire soon. In a letter to Stadium Authority executive director Mary Conturo Monday, Mr. Stabile offered $10 million "with no contingencies" for a 3.3-acre parcel bordered by North Shore Drive, West General Robinson Street, Dorsett Way, and Chuck Noll Way. He said the existing purchase price option for the land is $1 million.

Mr. Stabile also offered the Stadium Authority $3 million for a 1.1-acre parcel on North Shore Drive near the former Equitable Building. He said the existing purchase option for the property is $600,000.

In his letter, he said he would like to market both parcels for build-to-suit office projects. Mr. Stabile is proposing a 10-story office tower on the 3.3-acre site that he said would "create a more dramatic skyline for the North Shore."

As part of his offer, he said neither Stadium Authority nor the city-Allegheny County Sports & Exhibition Authority would be responsible to build or pay for any additional parking on the North Shore as the parcels are developed. He also promised not to seek any public subsidies from the city, the county or the state.

Ms. Conturo could not be immediately reached for comment.