by the early 19th century, dredging and other improvements to the river foss had made it possible to import flour into york by river, reducing the economic significance of the castle mills. in 1856, the castle mills were finally demolished as part of a further sequence of improvements to this part of the river. the king's pool that formed part of the castle's water defences was drained. with the construction of several new bridges near the castle, the site became "surrounded by roads instead of moats". some major trials took place at the assizes (now crown court) building of york castle in the 19th century, including that of mary fitzpatrick who was accused of murder.