The union of Prince William and Catherine Middleton is being marked across the UK by a national holiday. The Nationalist Scottish Government announced, on 23 November, that Scotland would mark the public holiday too (see First Minister Alex Salmond's statement).
In Edinburgh, it means many (but not all) public services and shops such as libraries, shops and banks will be closed throughout the day.
The Royal Wedding is being livestreamed (from 10am on YouTube) and broadcast across the planet.
The above video is from the official announcement of the engagement on 16 November 2010 (should come with a health warning about flashing lights).
First Minister Alex Salmond's statement
"I extend my warmest congratulations to Prince William and Miss Middleton, as they look forward to a wonderful wedding day and the beginning of a long and very happy marriage.
The wedding day will take place during the Scottish election period, which has implications for the electoral and parliamentary timetable, and we will work through these in close consultation with the Holyrood authorities."