PROVIDENCE, R.I. (AP) — The Rhode Island Supreme Court is hearing arguments in a fight that has pitted dozens of members of the Vanderbilt family against a nonprofit that owns several Gilded Age mansions in Newport.

The arguments Tuesday morning are over issues that will affect the nonprofit's plan to build a visitors center on the grounds of the spectacular Vanderbilt mansion The Breakers, a national historic landmark.

Opponents include designer Gloria Vanderbilt and nearly four dozen other members of the Vanderbilt family, as well as dozens of preservationists. They have said the plan would "permanently mar this national symbol of Newport's Gilded Age."

The Preservation Society of Newport Country wants to build the visitors center to better serve its 400,000 annual visitors.