High voltage demonstration at the Deutsches Museum, Munich.

The equipment includes a 300KV AC transformer, and a 1MV Marx impulse generator, and is demonstrated three times a day.
More info here. Museum info with more images

300KV AC arcs (left to right) : point to point,  to faraday cage containing serious-looking German chap, arcs round the edges of 2ft x 1" glass plate, burn mark on glass.

Lightning discharge approx. 1 metre long from Marx generator to model house. Notice leaders (arrowed) which didn't make it. VERY LOUD!

Vaporising a metre of copper wire, Marx generator, closeup of Marx sparkgaps.

Megavoltmeter on control panel!