A group of companies that owns about half of the theaters on Broadway said yesterday that it had revamped 16 properties, all of them historical landmarks, to make them more accessible to theatergoers with disabilities.

The Shubert Organization, whose theaters include the Winter Garden and the Barrymore, has spent about $5 million to rebuild auditoriums, bathrooms and ticket counters in 16 theaters, said Gerald Schoenfeld, the group’s board chairman.

The changes bring the theaters into compliance with the Americans With Disabilities Act, which requires that public buildings provide access for the handicapped, said Robert W. Sadowski, the assistant United States attorney for the Southern District of New York. His office had recommended that theaters make the changes, which the owners eventually agreed to do.

“What we did was a combination of compulsion and volunteerism,” Mr. Schoenfeld said at an opening ceremony near one of the newly upgraded theaters. “We were a willing complier.”

Kevin McGuire, a consultant on the theater upgrades, has been in a wheelchair since 1968 when, as a child, he was struck by a drunken driver. Watching a Broadway show or a movie, he said, meant sitting in raked aisles while “people got their share of popcorn and soda on your shoulder.”

To upgrade the theaters, builders unbolted some seats, making space for wheelchairs. The slope of the floors was adjusted with concrete. Slots were cut into the marble walls below ticket counters to enable people in wheelchairs to turn over credit cards and cash. Bathroom stalls were widened.

All 16 theaters are landmark buildings, with an average age of 80 years.

The age presented problems for the designers, who had to contend with narrow aisles and sloped floors. Regulations imposed by the Fire Department had to conform to historical landmark requirements.

The Americans With Disabilities Act went into effect in 1992. Under the rules, new buildings must make 1 percent of their seating available to people in wheelchairs, Mr. Sadowski said. For older buildings, however, the rules are less clear. They state that buildings should be made accessible where access is “readily achievable.”

The group began working on the reconstruction in 1996 after the federal government recommended the changes.

The owners of some public structures have resisted making such changes. The federal government had to sue Yankee Stadium in 1999 before its owners finally agreed to comply, Mr. Sadowski said.

Even so, New York has come a long way since the 1970’s, when, Mr. McGuire remembers, his father had to carry him over rows of seats to see a Knicks basketball game. Even a decade later, as a college student in Rhode Island, attending an Earth Wind and Fire concert with friends was a lonely experience.

“It was bizarre,” he said. “I had to sit off by myself.”