Downing Street mortar attack
The Provisional Irish Republican Army (IRA) launched three homemade mortar shells at 10 Downing Street, London, the headquarters of the British government, on 7 February 1991. The goal was to assassinate Prime Minister John Major and his war cabinet, who were meeting to discuss the Gulf War.
Source: Wikipedia — Downing Street mortar attack (CC BY-SA 4.0)