Which building did the Gunpowder Plot conspirators plan to blow up on 5 November 1605?

The Gunpowder Plot conspirators planned to blow up the House of Lords on 5 November 1605.

The House of Lords occupied part of the medieval Palace of Westminster, where the English Parliament met. The conspirators rented an undercroft directly below the chamber and moved gunpowder into it. They intended the explosion to happen during the State Opening of Parliament, when the king, lords and leading officials would be gathered.

The target was chosen because destroying Parliament could kill the political leadership at once and create an opportunity for rebellion. Guy Fawkes was found in the undercroft before the ceremony began, preventing the attack.

The phrase “blow up Parliament” is often used as a general description, but the specific intended target was the House of Lords. Westminster Abbey and the Tower of London were nearby historic sites, not the building selected for the plot.