Colen Campbell is the architect most credited with the design. However, later investigation and studies show that his first works on the design are dated from 1723 CC onwards, which using the modern calendar would be from March 1723 onwards. Campbell can be connected to the project, but his initial and later designs show his preferred Wilton-style towers, as published by him in "Vitruvivs Britannicus" in 1725. However, the final design of the tower domes was undertaken by James Gibbs, with: the south-west tower dated 1725; the south-east 1727; and the others dated from 1729. Both the interior and exterior were extravagant, later estimated by Walpole himself to have cost over £200,000 - he admitted to burning most of the receipts, adding further to being unable to verify the architecture timeline. The best materials and designers were employed, including William Kent who designed the ceilings for the reception areas and ground floor, as well as some furniture. In the context of the day, it should also be noted that Campbell, Gibbs and Kent were not just rivals, but very much disliked each other. It is perhaps hence understandable that Ripley's own records show that he took a larger role in the project during the later stages of construction of the external edifices, with his drawings showing him greatly altering the earlier works of both Cambell and Gibbs.