While several architects were invited to strut their stuff at last month’s London Design Festival, John Pawson chose cleverly to show off instead the work of Sir Christopher Wren, and that deflection attracted all the more attention.

In a usually off-limits corner of St. Paul’s Cathedral, the less-is-best architect placed a baptismal-like drum with a polished steel surface beneath the coiled Geometric Staircase. Working in collaboration with Swarovski, he placed atop the mirror not one of their famed sparkly crystals—“I wasn’t going to use those!”— but a liquid smooth 400 millimeter-wide precision concave lens. (Forget the chandeliers, the company makes its real money on military telescopes and medical microscopes.) With a spherical concave mirror positioned at the top of the stairs, the reflection allows a sumptuously close reading of the underside of Wren’s meticulously carved Portland stone stair. Every inch the Enlightened Man, Wren himself loved scientific instruments and might have been first in line to enjoy the minimalist spectacle here that is in honor of the 300th anniversary of the cathedral’s completion. Visitors to London can join his ghost in the South West Tower through January 2012.