Lambert Castle, originally called Belle Vista, is located within the Garret Mountain Reservation in Paterson, Passaic County, New Jersey.

The building was built in 1892 and was added to the National Register of Historic Places on June 3, 1976, for its significance in art, architecture, and industry.

Constructed in the Medieval Revival architectural style, Mr. Lambert's dream was to build a home reminiscent of the castles in Great Britain that he remembered from his boyhood years.

In the late 1990s, the Castle underwent a multimillion-dollar restoration and all four floors of the building were developed into a museum and library.

[5] In 1896, an art gallery was added to the castle and a 70-foot observation tower was constructed on the crest of the cliff.