The New Jersey (search) post office that handled anthrax-laced letters reopened Monday morning, nearly 3 1/2 years after the deadly mailings that further heightened the nation's fears in the weeks after the Sept. 11 terror attacks.

The opening had more the air of a gala than a normal day at a post office. Officials were on hand with cake, and the low-slung building was decorated with balloons.

The post office was closed on Oct. 18, 2001, after NBC anchor Tom Brokaw (search), two U.S. senators and the offices of the New York Post received anthrax-laced letters that went through Hamilton.

In all, the anthrax (search) attacks killed four people across the country and sickened 17. There were five confirmed anthrax infections and two suspected cases in New Jersey, but no fatalities. Investigators have not determined who was responsible for the attacks.

The center was stripped to its bare walls in a renovation with an estimated cost between $80 million and $100 million. All the furniture and mail-sorting equipment was replaced.

The building was fumigated early last year with chlorine dioxide gas to kill any remaining anthrax spores.

The building now has sensors to detect anthrax and other biological agents — a feature that all the nation's postal distribution centers are due to receive.

Of the roughly 500 Hamilton postal workers, about 10 have said they will not work in the old building, said the president of their union. Those workers can be moved to other postal centers. The four workers who were infected there have not returned to work and are not expected to return to the old building.