Dunnellen Hall is a private mansion located at 521 Round Hill Road in Greenwich, Connecticut, USA.

[1] Dunnellen Hall was built for New York City financier Daniel G. Reid as a gift for his daughter in 1918.

Leona Helmsley would live in Dunnellen Hall until her death in 2007.

Two outdoor fountains, including a large external front entrance one, were also removed.

Many of the interior rooms were refurbished and/or updated to a more modern appearance, removing the darker mahogany wood tones of the Helmsley era.