The Princes Street Gardens run east-west through the center of Edinburgh, dividing the Old Town from the New. I guess it used to be a waterway, but people started throwing in garbage and making it stink, so they drained it and went with gardens.
The gardens are well manicured and it makes for a pleasant walk. There are excellent views up to the Castle and the Royal Mile (High Street). There is the Scottish Monument to Sir Walter Scott (below). There are cute concession stands and people lounging about. Not sure they will be there when it starts raining, but I have yet to believe it will, considering the last 2 weeks of sunshine.