The renowned Spanish architect contends in his suit filed in Cook County Court the building's developer, Shelbourne Development Ltd., owes him $11.3 million for his work on the project, which would be the United States' tallest building, the Chicago Sun-Times reported Saturday.

The newspaper says a Chicago architectural firm, Perkins & Will, which was hired as a local overseer of the design, has also filed a lien, claiming it is owed $4.85 million.

Ground has been broken on the North Lake Shore Drive project but Shelbourne has acknowledged slowing its pace in the wake of the meltdown of the global financial markets.

"We've paid (Calatrava) a significant amount of money, and this is a four-year project," Kim Metcalfe, a spokeswoman for Shelbourne, told the Sun-Times. "We are working proactively with him to resolve this."