Castle Heights Military Academy was a private military academy in Lebanon, Tennessee, United States. It opened in 1902 and became a military school in 1918. The school closed in 1986. Its former campus was placed on the National Register of Historic Places as the Castle Heights Academy Historic District in 1996.

The academy was founded in 1902 as Castle Heights School outside of Lebanon, Tennessee. Its founders were David Mitchell, president of Cumberland University; Isaac W. P. Buchanan, a mathematics teacher at the recently defunct Cumberland Preparatory School; Amzi W. Hooker, a resident of Lebanon; and Laban Lacy Rice, a former English instructor at the Cumberland Preparatory School.

Rice served as the school's headmaster and was later president of Cumberland University. Buchanan taught mathematics at the school and was later its business manager and headmaster. The academy was initially coeducational and had 96 boarding students. It became a military preparatory school for boys in 1918 as a response to World War I. By the next year, the military academy had 415 cadets.

In 1928, Castle Heights Military Academy struggled financially and was bought for $100,000 by Bernarr Macfadden, a millionaire publisher. physical trainer, and nationally known fitness advocate. He hired Harry L. Armstrong as the academy's superintendent, and Daniel Taylor Ingram, a Virginia Military Inistitute graduate and former assistant commandant of Fishburne Military School, as its commandant. Macfadden required the students to eat salads every day, not to use condiments or pillows, to participate in sports, and to drink so much milk that the school acquired a dairy. He also introduced boxing and wrestling programs. Students' height and weight appeared on their monthly report cards.

In 1954, the school had grown to almost 500 students and operated a summer camp. After Mcfadden's died in 1955, the academy was operated by The Bernarr Macfadden Foundation. Sanford Naval Academy was founded in Sanford, Florida, as a sister institution in 1963. In 1965, Ingram became the academy's superintendent, after serving as its commandant since 1929.

In 1973, the school began admitting female day students. The Castle Heights Foundation purchased the school in 1974. The school ceased operations in 1986 in the face of declining enrollment and debt. Cumberland University maintains records and other school memorabilia.

Many of the former academy's buildings have been restored and now house the Lebanon City Hall, Lebanon Museum and History Center, and other small businesses. Previously undeveloped areas of campus have been subdivided and now are the location of businesses, such as banks and nursing homes. The Mitchell House served as the headquarters of the holding company for Cracker Barrel Old Country Store from 1998 to 2013. It was purchased by Sigma Pi fraternity in 2013 and served as its international headquarters until 2017.

Castle Heights Academy's administrative building was designed by architect Tom Chamberlain in the Gothic Revival style in 1902. The Queen Anne style president's house was building in 1902, west the administrative building. Rutherford Parks Library and Mildred Armstrong Hospital were added in 1905, both in collegiate gothic style.

An auditorium and gymnasium were built in 1928 and named for the school's owner, Bernarr Macfadden. The Mitchell House, the former home of founder David Mitchell, was purchased by the school in 1936 and used to house the junior school; it was called Macfadden Hall. Behind the Mitchell House was a springhouse that was used for gun storage. The campus included 150 acres and was expanded to 225 acres in the 1930s. The McFadden Foundation Auditorium was added to the campus in 1941.

The campus was added to the National Register of Historic Places as the Castle Heights Academy Historic District in 1996.

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• List of defunct military academies in the United States
• National Register of Historic Places listings in Wilson County, Tennessee

• Alumni association
• National Register of Historic Places entry for Castle Heights

36°12′47″N 86°18′22″W / 36.21306°N 86.30611°W / 36.21306; -86.30611