St John's Smith Square is a redundant church in the centre of Smith Square, Westminster, London. Sold to a charitable trust as a ruin following firebombing in the Second World War, it was restored as a concert hall.

This Grade I listed church was designed by Thomas Archer and was completed in 1728 as one of the so-called Fifty New Churches. It is regarded as one of the finest works of English Baroque architecture, and features four corner towers and monumental broken pediments. It is often referred to as 'Queen Anne's Footstool' because as legend has it, when Archer was designing the church he asked the Queen what she wanted it to look like. She kicked over her footstool and said 'Like that!', giving rise to the building's four corner towers.