First off, if you don't like modern architecture, give this place a miss. If you are OK about that though, and passing through Liverpool Street, it's well worth a visit. Hidden away in the midst of some rather good examples of modern architecture it's a very unusual open space. Rather than a normal square, what you have here is mostly a range of steps, facing the end of the station platform, and a stage area (which I've never actually caught being used though I'm told it is). Any day around mid day the steps will be filled with office workers eating their lunches. There's also a big water feature: a series of very non-natural waterfalls. Sitting there the noise of the water is very soothing, though I can never help wondering how many chemicals are needed to keep the stones free of algae!
Anyway it's different. It's also only part of a network of pedestrian spaces to the North and West of Liverpool Street Station, including some shops and sculptures. You may wish to wander read more