Occasional faults, strikes and overcrowding aside, the London Underground is a truly fantastic thing. A marvel of modern engineering and ingenuity, for everything that we sort of dislike about it there's always at least two other things that you probably love.
Here's a nerdy celebration of the tube system in all its imperfect glory, revealing their floor plans and '3D' structure. It has several benefits: firstly, that they look nice. Secondly, that they provide you with the inside loop on all of the secret short cuts that you're probably missing out on at the moment.
Oxford Circus is particularly enlightening.