The Middle Ward is dominated by the Round Tower, originally an eleventh-century Norman keep built on a man-made mound or motte. Sandby's watercolours show the Tower before it was raised by about 9 metres (30 feet) under the instruction of George IV (1820-1830). Sandby often made versions of his views in bodycolour, mixing white pigment with watercolour to make it thicker and more opaque.