Gruul's Lair is a cave system in northern Blade's Edge Mountains, formerly known as Gorgrond. The massive caverns played host to the mighty Gronn and their late ruler, Gruul. During the invasion of Outland, the caves served as unofficial capital of the mountains as the Gronn-Lord commanded his Ogre slaves to expand his reach and remove all outsiders from Blade's Edge.
The age of the caverns is unknown, yet noticeably, the caves occupy the same location on Outland as the ancient Blackrock Foundry did upon Draenor. If the locations are indeed the same, then Gruul's Lair would in fact be the ancient home of the Blackrock Clan, and the same system of caves which sheltered the bulk of the Orcish race during the Age of Colossals. This would make it the true first home of the Orcs. It is possible that Gruul took over the caves at some point after the Doom of Draenor.