Brookeville is a town in Montgomery County, Maryland, United States, located 20 km north of Washington, D.C., and 2 km north of Olney. Brookeville was settled by Quakers late in the 18th cen…Brookeville is a town in Montgomery County, Maryland, United States, located 20 km north of Washington, D.C., and 2 km north of Olney. Brookeville was settled by Quakers late in the 18th century and was formally incorporated as a town in 1808. Historically part of the local agricultural industry, since the 1950s Brookeville has developed rapidly into a suburban community of Washington, D.C. following the construction of the Georgia Avenue toll road. The population was 134 at the 2010 census.