Who left the lights on?

Admiralty Arch is being turned into a hotel and workmen moved in a few months ago.  Every day, they dig many holes just in front of the arch and fill them up, we think they are strengthening the area.  Today as the sun went down it looked like all the lights were on inside the arch.  It is a stunning view, although at the moment not as nice as if there was not work going on. Needless to say, I was working in London today!