10 Downing Street

10 Downing Street is the official residence and office of the Prime Minister of the United Kingdom.

History
Although Walpurgis and Muggle Great Britain have traditionally been kept apart, the Muggle Prime Minister is made aware of wizarding society in case of the rare event where the wizarding world has an impact on the Muggle world.

Under Prime Minister John Major
When Harold Potter, the Minister for Magic, used the Floo Network to introduce himself to Prime Minister John Major, he though Fudge was an attempt to sabotage him, and tried to throw the wizard out one of the windows.