Sonnenberg Gardens and Mansion State Historic Park is a 50-acre (20 ha) state park[3] located at 151 Charlotte Street in Canandaigua, New York, at the north end of Canandaigua Lake, in the Finger Lakes region of Upstate New York.

The nephew who inherited the estate after Mary Clark Thompson's death in 1923 sold the property to the Federal Government in 1931, who built a veteran's hospital (today the Canandaigua VA Medical Center) on the adjacent farmland.

In 1972, by an act of Congress called the Sonnenberg Bill, the mansion and its grounds were transferred from the Federal Government to a local non-profit organization formed to restore and reopen the property.

Today most of the gardens have been restored, as follows: Built between 1885 and 1887, the 40-room Queen Anne style mansion was designed by Francis R. Allen, a noted Boston architect.

[4] The mansion's facade is rusticated graystone with Medina sandstone trim and gables made from timber and stucco.