It might be about 150 years late, but The Antiquities of Athens has been returned to the New South Wales library from where it was borrowed.

The book was discovered in a tea chest bricked into a fireplace by a family renovating their home in Kiama, on the state's South Coast.

"The family has been in Kiama a long time and discovered this as part of unveiling the old fireplace in the house," Kiama Library manager Michelle Hudson said.