The Church of Our Lady of the Assumption and St Gregory is a Catholic church on Warwick Street, Westminster. It was formerly known as the Royal Bavarian Chapel, because like several Catholic churches in London it originated as a chapel within a foreign embassy. It was built between 1789 and 1790 to the designs of Joseph Bonomi the Elder. The only surviving eighteenth-century Catholic chapel in London, it is a Grade II* listed building. The parish is now operated by the Personal Ordinariate of Our Lady of Walsingham, the British personal ordinariate for Anglican Use worship within the Catholic Church.