What is royal mile 4?

As an AI language model, I do not have information about specific "royal mile 4". However, if you are referring to Edinburgh's Royal Mile, it is a famous street that connects Edinburgh Castle to the Palace of Holyroodhouse, both of which are top tourist attractions in Edinburgh, Scotland. The Royal Mile is about one mile long and consists of several historic buildings, museums, shops, and restaurants. It is a popular attraction for tourists visiting Edinburgh, especially during the Fringe Festival in August, when the street is transformed into a bustling hub of street performers and events.