In St Paul's Cathedral in London there is a highly complex system of vaults and faux-vaults. The dome that one sees from the outside is not a vault, but a relatively light-weight wooden-framed structure resting on an invisible – and for its age highly original – catenary vault of brick, below which is another dome, (the dome that one sees from the inside), but of plaster supported by a wood frame. From the inside, one can easily assume that one is looking at the same vault that one sees from the outside.
In St Paul's Cathedral in London, there is a complex system of vaults and false vaults. The exterior dome does not constitute a true vault but rather a lightweight wooden-framed structure resting on an invisible – for its age highly original – catenary brick vault beneath which lies another dome (the one seen from inside), made of plaster and supported by wood. From the interior, it seems as if you are viewing the same vault visible from outside.