The property containing the nation's most revered cemetery had a very rich and turbulent history. Originally, the property was the estate of George Washington Parke Custis, who was President Washington's step-grandson. He completed his house in 1818, after beginning construction in 1802. His only child, Mary Anna, inherited the estate after marrying the future Confederate General Robert E. Lee.
Custis-Lee mansion:
After Virginia's secession from the Union, the Lees evacuated to safer places and the property was occupied by Federal forces.
Union troops occupy the Lee residence:
In 1864, the US government seized the estate after refusing Mrs. Lee's tax payment, saying that she needed to pay it in person.
General Montgomery Meigs, who hated General Lee, proposed a cemetery be built on the site, and deliberately located graves as close to the house as possible in order to make the place unlivable.
Burial vault of unknown Civil War soldiers in Mrs. Lee's rose garden:
"Arlington National Cemetery was established by Brig. Gen. Montgomery C. Meigs, who commanded the garrison at Arlington House, appropriated the grounds June 15, 1864, for use as a military cemetery. His intention was to render the house uninhabitable should the Lee family ever attempt to return. A stone and masonry burial vault in the rose garden, 20 feet wide and 10 feet deep, and containing the remains of 1,800 Bull Run casualties, was among the first monuments to Union dead erected under Meigs' orders. Meigs himself was later buried within 100 yards of Arlington House with his wife, father and son; the final statement to his original order."
http://www.arlingtoncemetery.mil/History/Facts/ArlingtonHouse.aspx
General and Mrs. Lee's son, George Washington Custis Lee, sued the government to recover his inheritance, and in 1882, the US Supreme Court ruled that Arlington had been illegally confiscated. Faced with having to exhume 17,000 graves, the government negotiated with Custis Lee and ended up purchasing the property from him in 1883 for $150,000.