 As the Inn grew it became necessary ( for safety purposes ) to wall off the land owned by the Inn , which had previously been open to everyone . In 1591 the " back field " was walled off , but little more was done until 1608 , when under the supervision of Francis Bacon , the Treasurer , more construction work was undertaken , particularly in walling off and improving the gardens and walks . In 1629 it was ordered that an architect supervise any construction and ensure that the new buildings were architecturally similar to the old ones , and the strict enforcement of this rule during the 18th century is given as a reason for the uniformity of the buildings at Gray 's Inn . 
