Sir Christopher Wren's masterpiece was topped-out exactly 300 years ago. As part of this year's Festival one of the UK's leading architects, John Pawson, has designed an installation complementing Wren's intention that each of his buildings should include a scientific element. A metal and Swarovski crystal half-hemisphere at the base of the Geometric Staircase in the South West Tower, will allow visitors a greater view of the cathedral than the natural eye could see.