The Queen is to officially open the new railway line between Edinburgh and the Borders on the day she becomes Britain's longest-serving monarch.
She and the Duke of Edinburgh will be accompanied by First Minister Nicola Sturgeon on a steam train journey along the £294m line, the UK's longest domestic line to open in a century.
Specially-selected passengers got a sneak preview of the route on Saturday.
The line between Tweedbank and the capital was publicly-opened on Sunday.
After the Queen formally opens the line, she will pass Queen Victoria's record to become Britain's longest reigning monarch.
Buckingham Palace has calculated Queen Victoria reigned for 23,226 days, 16 hours and 23 minutes.
The Queen is scheduled to pass that record at about 17:30.
The royal party will leave Edinburgh in the morning and is due to arrive at the Tweedbank terminus for the official opening ceremony around lunchtime.
The public will be allowed entry to the Tweedbank station car park, which is being used as the spectator area. Entertainment is expected to start around 10:30.
Source: BBC