Baynard's Castle refers to buildings on two neighbouring sites in the City of London, between where Blackfriars station and St Paul's Cathedral now stand. The first was a Norman fortification constructed by Ralph Baynard, 1st feudal baron of Little Dunmow in Essex, and was demolished by King John in 1213. The second was a medieval palace built a short distance to the south-east and later extended, but mostly destroyed in the Great Fire of London in 1666. According to Sir Walter Besant, "There was no house in [London] more interesting than this".

The Great Fire of London was a major conflagration that swept through central London from Sunday 2 September to Thursday 6 September 1666, gutting the medieval City of London inside the old Roman city wall, while also extending past the wall to the west. The death toll is generally thought to have been relatively small, although some historians have challenged this belief.