Drum Revolve

I have been having a look at the drum revolve situated in the Olivier theatre in the National Theatre in London.  It is a pretty amazing piece of kit. 

It was built in the 70's with the building but wasn't used until the mid 80's before falling out of use in the 90's. In had a refurb in 2002 and is currently being used. 

The drum revolve, as its name denotes, is a giant rotating stage. But beneath its surface is something more interesting: two large elevators, which can be raised and lowered 8m below stage level, allowing huge pieces of scenery to be loaded via four large scenery doors. The disk which can be fixed to the stage or driven directly with the drum itself, makes up half of the stage, while the other half is raised, using either elevator. 

how the drum works (explains how the drum works and how change overs happen). 

Its really very impressive and i would love to see it in action. I really love how it can be used for so many things. Also the scale is pretty immense 4 stories high with a 15m diameter almost bigger than the whole of the stage in the Ath.