The architect extended the building over 30 years; the first phase was only three windows wide. The main room was the first floor studio, facing north, originally 45 by 25 feet, with a large central window to provide plenty of light for painting. There was also a gallery at the east end, and a separate staircase for use by models. The house was extended to the east in 1869–70. Additionally, a major extension was made in 1877–79: the two-storey "Arab Hall," built to house Leighton's collection of tiles collected during visits to the Middle East.