Ickworth was originally granted to the monks of St Edmundsbury via the Bishop of Hoxne's Will in AD995, but the estate was granted to a tenant, William Drury, during the reign of Henry VI. Through his only daughter's marriage, the long line of succession by the Hervey family began at Ickworth in 1467, and they remained in ownership until 1956 when the property was transferred to the National Trust.

Little is known about the original manor house that stood on the estate, except that it was built during the 15th or early 16th century. When John Hervey (later to become the first Earl of Bristol) inherited the property he consulted with Vanbrugh about his plans for rebuilding the old house. Intending to site the grand new house just north of the original plot, he demolished the earlier manor house in 1710 and moved into one of the estate's farmhouses. His plans never came to fruition and, in fact, it was a further 80 years later before work commenced on the palatial house as seen today.

It was when his grandson, the Bishop of Derry (4th Earl of Bristol), decided to settle at Ickworth after his extensive European travels that this grand building scheme began. Already owning numerous properties in Ireland, he viewed Ickworth more as a museum than a comfortable residence and looked to fill this curiously designed house with his collections of fine paintings, silver and furniture. As well as being an avid collector, the Earl-Bishop had developed a passion for oval and circular buildings. Thought to have been influenced by a circular house seen near Lake Windemere, the oval rotunda at Ickworth House began to take shape in 1796, but just two years later the Bishop's collections were seized by the French during Napoleon's campaign in Italy. At the time of his death in 1803 the great rotunda was all but completed, but the walls of the curving wings had hardly began. It was in these corridors that the Bishop's treasures should have been exhibited. His son completed Ickworth House some years later, moving into the east wing of the remodelled mansion in 1829.

Much of the house reflects the neo-classical style, but the Pompeian Room (designed by J D Grace) provides a wealth of varied and stunning decoration based on some Roman wall paintings uncovered in 1777. Quality portraits and paintings are to be found everywhere, many of them Masterpieces, and other splendid treasures, such as the pair of ornate Italian pier glasses and tables between the windows in the dining room. From the wide, oak staircase there is a splended view of the unfinished inside of the dome, and an interesting perspective of the extraordinary height of the rooms. Much improvement and restoration was carried out at the beginning of the 20th century to leave Ickworth House the outrageous showpiece it once represented, surrounded by formal gardens, parkland and many acres of woodland.