Many plans, drawings and architectural models were made as the Wren Office explored how the building could be achieved. 226 drawings survive in the cathedral collection, some are by Wren himself, and at least thirteen other individuals, who helped to design the cathedral, have been identified, including: Nicholas Hawksmoor, Edward Woodroofe and Edward Pearce.
The design of the dome was a particular challenge for Christopher Wren. It was a radically new type of architecture for England, so innovative that he had to continuously rework the design as the building was going up. He called on the expertise of friends in the Royal Society, such as Robert Hooke and Isaac Newton, for help.
This drawing from the 1680s was made when the cathedral had been built up to the base of the drum of the dome. Here you can see the inner and outer domes which Wren wished to build but at this stage the addition of a brick cone between the two domes, to take the weight of the lantern, has yet to be thought of.