The six tonne cannon was transported from Edinburgh Castle for specialist restoration and conservation work.
Mons Meg was lifted by crane in the morning, in a tightly-controlled operation involving specialist personnel. She has now been moved off-site and, over the next few weeks, will be carefully examined by Historic Scotland’s expert conservation team.
Richard Welander, Head of Collections for Historic Scotland said: “Mons Meg undergoes regular ‘health checks’ each year and is lifted off its carriage every five years for a closer inspection. 
“This time it’s getting a major service, which means it must leave the castle for the first time for 30 years. The last time Mons Meg left was in March 1985, when she went to the Royal Armouries research establishment in Kent for a short technical examination.
“We’ll be using state-of-the-art equipment to examine the cannon and carriage inside and out, to assess their condition. Then we’ll commence with treatment and restoration, which is a delicate and specialist task.
“We’re hopeful that she’ll be back on display at the castle by late February.”
Over the next few weeks, the cannon will be closely assessed by conservators, including a laser scan and 3-D examination. The existing paintwork will be removed using a high pressure water system in combination with bead blasting. The iron surface revealed will then be examined, cleaned and dried carefully, before being re-painted using a protective paint system by Historic Scotland painters.
The oak carriage that Mons Meg sits on will also undergo some conservation and repair works by Historic Scotland joiners. The carriage was built in 1934 and cost the Lord Provost of Edinburgh £178 at the time.
The Historic Scotland team will also use the time off site to uncover the truth behind some of Mons Meg’s mysteries.
Richard Welander explained: “Obviously in the past we didn’t have the technology which we have today, so there are now a number of techniques that can be applied which could potentially reveal different aspects of Mons Meg’s story.
“This gives us the opportunity to gather and verify more evidence on Mons Meg’s past, which is an exciting prospect.”
Despite many people believing that Mons Meg is fired each day at one o’clock, it is, in fact, a modern military cannon so visitors to the castle will still be able to see and hear the world-famous One o’clock Gun at Edinburgh Castle.
People can also track Mons Megs’ progress by following @edinburghcastle on twitter.