It almost looks as though this Vienna building is a net, catching fluffy white clouds in a blue sky.

Glass was first introduced into architecture around two millennia ago, although the building technology of the age meant it could only be used to fill small windows and let in a little light. By the medieval period, construction developments meant that glass could be used for decorative – as well as practical – purposes. The large windows of churches allowed plenty of scope for fancy stained glass designs depicting Biblical scenes in a rainbow of vibrant colors.