The Spitzer administration announced the settlement of all insurance claims at ground zero yesterday, ensuring that $4.55 billion will be available for rebuilding the World Trade Center site. The agreement, which the insurers described as the largest single insurance settlement ever undertaken by the industry, ended a protracted legal battle with insurers over payouts related to the terrorist attack. All the parties to yesterday's settlement signed confidentiality agreements barring them from saying how much each insurance company would pay. The train is now moving down the tracks," said Larry A. Silverstein, the 76-year-old developer who had leased the World Trade Center complex six weeks before the Sept. 11 attack. The Port Authority of New York and New Jersey, which owns the land at ground zero and built the trade center, will get about $870 million from yesterday's settlement, which is to go toward the cost of erecting the $3 billion Freedom Tower. Mr. Silverstein will get the remaining $1.13 billion. The insurance battle has been complicated from the start by the circumstances of Mr. Silverstein's lease of the trade center and the destruction of the complex by terrorists six weeks later. At that time, two dozen insurers had signed binders pledging to provide $3.5 billion in insurance coverage, but had not finished the documents. An ugly dispute developed over which insurance policy was in effect at the time of the attack.