For an entertaining and informative overview of and introduction to the principal attractions of Edinburgh, consider the tour buses that leave every 20 minutes or so from Waverley Bridge (near Waverley railway station). The double-decker open-top motor coaches pass many of the major sights along the Royal Mile, the Grassmarket, Princes Street, and George Street. Three tours - Edinburgh Tour (green buses), City Sightseeing (red buses), and Mac Tours (vintage buses) - all cover roughly the same ground in Old Town and New Town. The Majestic Tour makes shorter work of the city center but includes Leith. Tickets can be used for 24 hours, and you can hop on and hop off the bus at designated stops.