Blackrock Hold was originally created out of dirt by Rythian and Zoey when they started their Tekkit series. Rythian then put a mining base under the fort for gathering materials. The fort got an upgrade when Rythian and Zoey replaced the dirt with cobblestone. Rythian then flattened the area around the fort with his destruction catalyst before he and Zoey decided to go mining. Going down their mine, they found an ominous sign that scared both of them, saying that they had "dug too deep" and that something had awakened.
After finding a "baby" volcano in a nearby taiga biome, Rythian decided to make the fort out of basalt bricks and starts work on it. The duo soon put in a marble brick floor and added a second story to the castle. Once the two stories of the fort had been made, Zoey built a logo on the outside of the fort, worked on the interior design, and began construction on Rythian's Sorcerer's Tower. The Sorcerer's Tower was never finished, as Teep was kidnapped by Sjin and she left after rescuing him.
During the time afterwards, Rythian left the castle badly maintained, and had resorted to testing various weapons of mass destruction, as that was all he felt necessary to do. When Rythian confronted Duncan at his own castle, he learned that the scientist had planted remote-activated nuclear devices under the castle. After escaping, Rythian retreated back to Blackrock Hold and found it badly damaged from what he identified as Dragonfire.
Since Zoey and Teep's return, they have begun the process of returning Blackrock Hold into its former glory while everyone thought they were defeated. This involved Rythian cleaning up the cobwebs, vines, and hedges that had sprung up around the castle while Zoey started fixing the farm and planning a way to deal with the nuke underneath the fort. Rythian has finished Season 2 of the Tekkit series. It ended with Zoey disarming the nuclear bomb. She was talking to Fishton, her instrument, when she cut the wrong wire, she panicked and called for Rythian, and the episode ended with an explosion sound.
At the beginning of Season 3, Rythian brings Duncan to Blackrock and it is revealed that it is now a massive crater, but it does not seem to have any irradiated blocks in the hole. At the end of S3E3 Rythian says that it is time to return. The next episode ends on a cliffhanger that has Rythian, Zoey, Teep, and Ravs (who is following them to the site) beginning to climb the hill that blocks the view of Blackrock from the Crooked Caber and has some ominous words about the site of the castle. Upon arriving at the site in episode 5, it is discovered that all that remains is part of Teep's tower and a section of the library tower. Rythian decides to leave the site due to Zoey's emotions about it and her blaming herself. It looks as if this is forever the end of the basalt castle.
One note, however, is that Duncan seems to have waypointed the crater for some odd reason. Maybe he has some plans for the site. Only time and future episodes will reveal what this means.