Old Town: medieval, steep, and stacked
The Old Town is the original medieval city, built along a single ridge running downhill from the castle. Its centrepiece, the Royal Mile, runs exactly one Scots mile between Edinburgh Castle at one end and the Palace of Holyroodhouse at the other. By the 1700s the Old Town was so overcrowded that some buildings reached fourteen storeys — an extreme height for the period, driven by there being nowhere to build except upward. Victoria Street, one of the Old Town's narrow curved streets, is often cited as an inspiration for Diagon Alley; J.K. Rowling wrote parts of the Harry Potter novels in Old Town cafés.
New Town: the planned answer, built in 1767
Around 1767, city planners laid out an entirely new district just north of the Old Town — wide straight streets, grand squares, and neoclassical Georgian architecture inspired by ancient Greece, centred on George Street, Queen Street and Charlotte Square. It's a genuinely different architectural language from the Old Town a few minutes' walk away, and together the two districts were recognised as a UNESCO World Heritage Site in 1995. Princes Street Gardens, laid out in the valley between them, gives a direct sightline up to the castle from either side.
Arthur's Seat: a wild hill inside the city
Arthur's Seat and the neighbouring Salisbury Crags sit directly against the Old Town — an extinct volcano you can be standing on top of within twenty or thirty minutes of leaving a Royal Mile café, with a view back over the whole city and the Firth of Forth. Very few capital cities put genuine hillwalking this close to their historic centre.
The one weekend you'll want to avoid
Every August, the Old Town becomes the epicentre of the Edinburgh Festival Fringe, the largest performing-arts festival in the world — extraordinary if that's specifically what you're after, but it triples accommodation prices and crowds every street in the neighbourhood this guide otherwise recommends walking slowly through. If a quiet, unhurried weekend is the goal, pick almost any other month.