Pratt had a number of estates and mansions designed.
William Tubby designed the Charles Millard Pratt House at 241 Clinton Avenue, Clinton Hill, Brooklyn in 1893.
Located in Brooklyn's Clinton Hill Historic District, it is one of the city's finest examples of Romanesque revival architecture.
The property is now owned by the Roman Catholic Bishop of Brooklyn.
Between 1921 and his death in 1935, Pratt spent "practically all his time" at 241 Clinton Avenue.

He also spent time at his estates outside of Brooklyn.
Pratt had a winter home, also known as Charles M. Pratt House, designed by architects Greene and Greene in Ojai, California and completed in 1909.
The winter bungalow was on a 54-acre estate as of 2001.
Architectural Digest described it as an “American masterpiece.”

In 1923, Pratt was said to be living at Seamoor, his summer estate, on the North Shore of Long Island in Glen Cove, New York.
Seamoor was designed by the New York firm of Lamb & Rich.
In 1903, a barn on the property burned down, killing 12 horses.
Pratt said the losses were covered by insurance.
By October 1930, the property's assessed valuation was around $7 million.
The Pratt estate also included the homes of nine members of the family: Representative Ruth Baker Pratt, Harold I. Pratt, Herbert L. Pratt, Charles Pratt, Frederic B. Pratt, George D. Pratt, F. L. Babbett and Helen P. Emmetto.

The large estate was later broken up.
In the late 20th century, a portion of the property was donated to the city of Glen Cove for use as a public park.
It has been developed for a golf course, tennis courts, a restaurant and related facilities.
Pratt had a number of estates and mansions designed. William Tubby designed the Charles Millard Pratt House at 241 Clinton Avenue, Clinton Hill, Brooklyn in 1893. Located in Brooklyn's Clinton Hill Historic District, it is one of the city's finest examples of Romanesque revival architecture. The property is now owned by the Roman Catholic Bishop of Brooklyn. Between 1921 and his death in 1935, Pratt spent "practically all his time" at 241 Clinton Avenue.
He also spent time at his estates outside of Brooklyn. Pratt had a winter home, also known as Charles M. Pratt House, designed by architects Greene and Greene in Ojai, California and completed in 1909. The winter bungalow was on a 54-acre estate as of 2001. Architectural Digest described it as an “American masterpiece.”
In 1923, Pratt was said to be living at Seamoor, his summer estate, on the North Shore of Long Island in Glen Cove, New York. Seamoor was designed by the New York firm of Lamb & Rich. In 1903, a barn on the property burned down, killing 12 horses. Pratt said the losses were covered by insurance. By October 1930, the property's assessed valuation was around $7 million. The Pratt estate also included the homes of nine members of the family: Representative Ruth Baker Pratt, Harold I. Pratt, Herbert L. Pratt, Charles Pratt, Frederic B. Pratt, George D. Pratt, F. L. Babbett and Helen P. Emmetto.
The large estate was later broken up. In the late 20th century, a portion of the property was donated to the city of Glen Cove for use as a public park. It has been developed for a golf course, tennis courts, a restaurant and related facilities.
Charles Millard Pratt