This building was the home of Arthur Underwood, his wife and his apprentice Nathaniel. It was in Highgate, an area of North London, and had was built in the Georgian era. It appears in The Amulet of Samarkand. When Simon Lovelace ordered Jabor and Faquarl to break Bartimaeus out of the Tower of London, knowing it was he who stole the Amulet of Samarkand, he followed Bartimaeus to Underwood's house to retrieve the amulet, despite Bartimaeus having apparently escaped the slip to the other two djinn.
Lovelace indeed found the amulet here, and, thanks to the amulet being extremely powerful and illegally obtained, he ordered Jabor to kill all witnesses to avoid a premature revelation to the government of his planned coup d'etat. As such, both Underwoods were killed and the house was destroyed, though Nathaniel escaped with Bartimaeus.