Washington lawmakers are investigating a number of private museums - including the Brant Foundation Art Study Center in Greenwich.

The Brant Foundation Art Study Center, owned by billionaire Peter Brant, holds some of the world's most valuable artwork, which is viewable by appointment only.

The museum is considered a tax-exempt museum by the IRS.

Sen. Richard Blumenthal says he will work with the Senate Finance Committee to determine if the Brant museum is simply a tax shield for Peter Brant, whose 200-acre estate sits directly across the road.

"Some of these foundations may be gaming the system, they may not be providing the public benefit that would justify the loss of public funds through these deduction[s]," says Sen. Blumenthal.

In 2013, tax returns show the Brant museum was worth nearly $94 million.

The foundation spent $2.5 million on charitable programs, some for public school children, but others for high-profile soirées featuring celebrity guests.

A spokeswoman for Peter Brant had no comment when contacted on Monday.