 Together with the 18th/19th-century New Town, it forms part of a protected UNESCO World Heritage Site.The "Royal Mile" is a name coined in the early 20th century for the main street of the Old Town which runs on a downwards slope from Edinburgh Castle to Holyrood Palace and the ruined Holyrood Abbey.Narrow "closes" (alleyways), often no more than a few feet wide, lead steeply downhill to both north and south of the main spine which runs west to east.