aerial photograph of Castle Howard Mausoleum Yorkshire England UK. Designed by Nicholas Hawksmoor , the Grade I listed mausoleum took 12 years to build from 1729 to 1741 and by the time it was completed both the architect and his client, the 3rd Earl of Carlisle, had passed away with the Earl becoming the first family member to be interred here in 1741. Image available for editorial use only.