 Harrison did not create an overall plan for his work on the site ; a series of plans for different buildings were prepared and building works continued until 1792 . The new buildings had to be placed between the existing medieval castle buildings , including the keep , towers and the gatehouse . Harrison decided to design them with Gothic motifs , such as battlements and windows with pointed heads . Construction started in 1788 , and the first building to be completed was the Keeper 's House , standing to the right of the gatehouse . The next substantial building to be completed was the Female Felon 's Prison on the other side of the gatehouse . He designed an arcade on the south side of the keep to give some shelter to the debtors as they walked round their courtyard . He later added two storeys to provide more accommodation for debtors , and completed the Male Felon 's Prison to the north of the keep . By 1794 these buildings and other improvements had cost £ 10 @,@ 853 ( equivalent to £ 1 @,@ 120 @,@ 000 in 2015 ) , more than had been expected . By 1795 Harrison had moved from Lancaster to Chester , from where he continued to supervise the work on both sites . At Lancaster this work included rebuilding the Crown Court and the Shire Hall . At that time the Crown Court was held in the medieval hall of the castle , and civil cases were held in the Shire Hall in the keep . The new buildings form a symmetrical group to the west of the keep , and were completed in 1798 , although the internal decoration and furnishings were not finished until some years later by Joseph Gandy . The Crown Court is a simple rectangular room , measuring about 50 feet ( 15 m ) by 30 feet ( 9 m ) high and wide . The Shire Hall has a plan of half a polygon about 80 feet ( 24 m ) in diameter . Six Gothic columns support a panelled vault covering the main part of the courtroom . Around the perimeter is an arcade , and the judge 's bench has an elaborate canopy in Coade stone . The precise cost of these buildings is unknown , but in 1807 an estimate of more than £ 40 @,@ 000 ( equivalent to £ 4 @,@ 550 @,@ 000 in 2015 ) was given . 
