The first building constructed on what was to become National Park Seminary was Ye Forest Inne, a resort for Washingtonians looking to escape the city's oppressive summertime temperatures. Hit by financial hard times, Ye Forest Inne closed its doors at the end of the 1892 season. The shingled Queen Anne style resort was purchased by John and Vesta Cassedy, who re-opened it as a girls' finishing school with a class of 48 female students in 1894. The Cassedy's instituted a 10-year building program, much of which was inspired by the 1893 Colombian Exposition in Chicago. Over the next 15 years, internationally styled buildings sprouted throughout the Campus as the school grew healthily - many of these unique structures such as the Dutch Windmill, Japanese Pagoda, Swiss Chalet, and English Garden Castle were built on a small scale, as they were initially used only as sorority meeting houses. Elaborate, well-tended gardens and winding paths kept the buildings connected and created a whimsical, almost playful feel to the campus. Dormitories, a chapel, and the Aloha house were also built. Ye Forest Inne, renamed Main, underwent extensive renovations to accommodate an exclusive higher learning facility; classrooms, boarding rooms, and several parlors were created, all of which were tastefully furnished. In 1901, the Odeon, a classically styled theatre, was built. An impressive colonial revival gymnasium, complete with a heated pool, bowling alley, and solarium was one of the last buildings constructed during the Cassedy era.

In 1916, John Cassedy sold his interest in the blossoming school to James Eli Ament. Ament, much like the Cassedy's, immediately started building. His first major building campaign in 1919 centered around improvements to Main. The building was expanded and connected to the outlying dormitories as well as the Chapel in an almost abrupt way, and the huge President's House was added to the Main at a 45-degree angle. In an attempt to unify the now monolithic building, which had taken on something of a cobbled look, the entire façade was covered in white pebble-dash stucco. Under Ament's guidance, the whole grounds were interconnected through ornate bridges and covered walkways in an attempt to "unify" the campus. The Aloha house received additions that more than doubled its existing size and was converted into a dormitory to accommodate a growing student body.

During his tenure, Ament undertook two other building campaigns; the first, in 1924, centered on a massive renovation of the Gymnasium. The changes turned the building from a colonial revival into an intimidating highly detailed neo-classical structure. It was covered in stucco and a massive Greek portico complete with Corinthian columns was added. The last major building campaign on the campus took place in 1927, when a ballroom of Ament's own design was built. The tallest building on the site, the ballroom was and still is seen as the crowning jewel of the campus. Along with various busts of prominent thinkers, leaders, and artists that could not be reached by vandals, the massive wooden speaker from the original Victrola record player still sits in the ballroom today. The Music Hall, built in a neoclassical style and linking the Main to the Odeon, was also constructed in 1927. At its peak before the stock market crash in 1929, National Park Seminary enrolled 400 young women and had an ample waiting list. It boasted tuition rates higher than both Harvard and Yale and catered to the highest socio-economic class in the country.

The school suffered during the depression, however in 1936 a new headmaster, Roy Tasco Davis began to take the school in a new direction with more modern principles of thought. The future of the school once again looked bright when the property was annexed by the army in 1942 for use as a medical facility.

Through three wars, soldiers were rehabilitated at National Park Seminary. The grounds sprouted military style cinder block buildings, and many of the lavish furnishings were auctioned off. The ornate covered walkways that once connected the campus were torn down, bridges collapsed, and the grounds, once elegant and graceful, began to overtake their surroundings. By 1978, the army had abandoned much of the complex in favor of newer facilities and many buildings fell into advanced states of disrepair due to poor, or non-existent, maintenance. Vandalism and theft increased at shocking rates.

Local preservation groups took action and in 2003 a development team led by The Alexander Company, a national leader in historic preservation and rehabilitation, took on the task of saving National Park Seminary and restoring it to its original glory, cementing its place once more as a true gem of the region as well as the country.