The Thompson Graving Dock in Belfast which is still there. In the upper pix, the
Olympic, sister ship to the
Titanic and the first one launched. Bottom pix as it is recently .. (I think the cardboard figures are just to emphasise the scale.)
These ships had two steam reciprocating engines driving the outer propellers and a steam turbine taking the exhaust steam from the other two engines to drive the centre prop. Consequently the centre prop could not go astern (which James Cameron picked up well in his film
'Titanic.')
I've been under a ship in drydock, trying to find the echo sounder sensor in order to coat it with grease prior to painting. You have to bend down to get under the hull, and definitely become aware of the colossal weight above your head.