The Doctor once slept in a barn as a child. He later returned to the site in four of his later incarnations, including on his return to Gallifrey after saving it in the Last Great Time War. The barn was located in the drylands of Gallifrey, near to the Capitol. (TV: Hell Bent)
During the First Doctor's childhood, he would retreat to the barn to cry so that the other children wouldn't hear him. On one such occasion, Clara Oswald used telepathic circuits to land the Doctor's TARDIS in the barn and comfort the Doctor, telling him the story of how he would return to the barn one day and that he should use fear to his advantage. (TV: Listen)
The War Doctor returned to the barn, bringing with him the Moment, which he intended to use to destroy Gallifrey, the Time Lords and the Daleks. However, the Moment opened a time fissure leading to his future to show him the consequences of his actions.
The War Doctor returned from the future with the Moment ready to detonate. Soon after his arrival, the Tenth Doctor, the Eleventh Doctor and a younger version of Clara Oswald arrived to assist him in Gallifrey's destruction. However, the Moment showed them the direct consequences of their actions and the Eleventh Doctor decided to alter their plan. (TV: The Day of the Doctor)
After returning to Gallifrey, the Twelfth Doctor returned to the barn and went into the loft where he slept as a child. A woman came in yelling at him that the things in the barn were for "the boys", but upon recognising him, told the Doctor that he would be killed for coming back to Gallifrey. Rassilon sent troops to the barn to kill the Doctor, but the Doctor won the troops over to his side and left the barn for the Capitol. (TV: Hell Bent)
Alternate timeline
In an alternate timeline, the Cybermen allied with Rassilon began rewriting history, following the War Doctor on his path to the barn. He faced them outside the barn (COMIC: Supremacy of the Cybermen) and once inside, hearing them calling his name, he activated the Moment. (COMIC: Prologue: The War Doctor)
During the Gallifreyan Cyber Fleet invasion, the Twelfth Doctor and Rassilon were put into the Cyber-converted Eye of Harmony to undergo conversion. During the process, Rassilon summoned the Doctor's consciousness in a virtual recreation of the barn, outside the rest of the Cyberiad, to elaborate a plan to stop the invasion. (COMIC: Supremacy of the Cybermen)