Broadway is the great planned axis of Letchworth Garden City, a broad formal avenue running through the civic heart of town. It is not dramatic in the way a cathedral close is dramatic, but it is the clearest place to see the garden-city idea translated into space.
Walk it slowly rather than just crossing it. The scale, verges, public buildings, and deliberate sense of air were all part of the point: this was meant to be an antidote to cramped industrial urbanism, not another accidental high street.