Places Off-Limits in Washington DC

A person issued a concealed carry license by the Chief, while carrying the pistol, shall not carry more ammunition than is required to fully load the pistol twice, and in no event shall that amount be greater than twenty (20) rounds of ammunition.
A person issued a concealed carry license by the Chief may not carry any restricted pistol bullet as that term is defined in the Act.
A licensee shall not carry a pistol while he or she is consuming alcohol.
A licensee shall not carry a pistol while impaired.
A building or office occupied by the District of Columbia, its agencies, or instrumentalities.
The building and grounds, including any adjacent parking lot, of an childcare facility, preschool, public or private elementary or secondary school or a public or private college or university.
A hospital, or an office where medical or mental health services are the primary services provided.
A penal institution, secure juvenile residential facility, or halfway house.
A polling place while voting is occurring.
A public transportation vehicle, including the Metrorail transit system and its stations.
Any premises, or portion thereof, where alcohol is served, or sold and consumed on the premises.
A stadium or arena.
A gathering or special event open to the public.
The public memorials on the National Mall and along the Tidal Basin, and any area where firearms are prohibited under federal law or by a federal agency or entity, including U.S. Capitol buildings and grounds.
The White House Complex and its grounds up to and including to the curb of the adjacent sidewalks touching the roadways of the area bounded by Constitution Avenue, N.W., 15th Street, N.W., H Street, N.W., and 17th Street, N.W.
The U.S. Naval Observatory and its fence line, including the area from the perimeter of its fence up to and including to the curb of the adjacent sidewalks touching the roadway of Observatory Circle, from Calvert Street, N.W., to Massachusetts Avenue, N.W., and around Observatory Circle to the far corner of Observatory Lane.
When a dignitary or high-ranking official of the United States or a state, local, or foreign government is moving under the protection of the MPD, the U.S. Secret Service, the U.S. Capitol Police, or other law enforcement agency assisting or working in concert with MPD, within an area designated by the Chief, the Chief of the U.S. Secret Service, or the Chief of the U.S. Capitol Police, or a designee of any of the foregoing, that does not include any point at a distance greater than 1,000 feet from the moving dignitary or high-ranking official.
When demonstration in a public place is occurring, within an area designated by the Chief or his or her designee, or other law enforcement agency, that does not include any point at a distance greater than 1,000 feet from the demonstration.
Any prohibited location or circumstance that the Chief determines by rule.
The carrying of a concealed pistol on private residential property shall be presumed to be prohibited unless otherwise authorized by the property owner or person in residential property.
The carrying of a concealed pistol in a church, synagogue, mosque, or other place where people regularly assemble for religious worship shall be presumed to be prohibited unless the property is posted with conspicuous signage allowing the carrying of a concealed pistol.
A licensee shall not carry a pistol openly or otherwise in a manner that is not concealed.
Any place where the carrying of firearms is prohibited by Federal Law.

SOURCE: https://www.gunstocarry.com/gun-laws-state/washington-dc-gun-laws/