The Blog of the Hobbit. Chances are, you do not know that much about it. The movie gives a brief explanation of its ownership and history, but it is very brief. And, unless you have delved in the more obscure and difficult of Tolkien's books, you have heard just as vague and brief description. So, that is why I am about to tell you all there is to know about this dark fortress and why there is such a big fuss about it in Middle Earth.
Sauron, it happened to be, was not the first inhabitant of this foul castle. Many ages ago, over 4000 years before Bilbo found the ring, Amon Lanc, the Bald Hill, the hill upon which Dol Guldur was built, was populated by elves. Then, Mirkwood was known as the Greenwood the Great, and Amon Lanc was the capital of the Silvan elves of Oropher, who was the father of Thranduil. During the Second Age, however, the elves gradually migrated north to the Emyn Duir, the Black Mountains, later known as the Mountains of Mirkwood. It is sometimes said that they felt the power of Sauron was growing again, and decided to flee. It is also said that they distrusted the strength of the Dwarves of Moria and the meddling of Galadriel and Celeborn in Lórien. Whatever the reason, Amon Lanc was deserted when Sauron came.
Construction on the fortress began around the year 1000 in the Third Age. It was named Dol Guldur, which means Tower of Dark Sorcery. Then, Sauron was only known as the Necromancer, still wary after his recent defeat. In 1050, a shadow fell across the Greenwood, and it soon came to be called Mirkwood. The Council of the Wise noticed the evil that had fallen across the forest. Sauron opposed taking any action, but in 2063 Gandalf the Grey journeyed to Dol Guldur. He discovered that the Necromancer was indeed Sauron. He informed the White Council, and they attacked Dol Guldur. Sauron, not yet possessing his full power, fled, and did not return for 400 years.
He did return though, in 2460, coincidentally the same time Smeagol laid his hands on the One Ring. He plotted his return to power for 400 years, and in 2845 imprisoned Thrain II, the King Under the Mountain in exile and keeper of a ring of power. In 2850, Gandalf journeyed there once again, and found a dying Thrain, who entrusted a map and key to Gandalf to be given to his son, Thorin Oakenshield. Thrain, however, had been driven mad, and could not even remember his own name. Gandalf confirmed that once again Dol Guldur was ruled by Sauron, and summoned the White Council. However, Saruman overruled his request to attack because he was searching for the One Ring in that area. In 2941, though, he consented to the invasion and Sauron was driven from Dol Guldur a second time. This was carefully timed to coincide with the quest of Bilbo and the dwarves, so as to not allow Smaug and Sauron ally themselves together and surely overrun Middle Earth. Sauron just relocated to the fortress of Barad-dur in Mordor, where he commenced his search for the One Ring.
Tolkein, J.R.R. The Hobbit UK: George Allen &; Unwin, 1937
Tolkein, J.R.R. The Lord of the Rings UK: George Allen &; Unwin, 1954-1955
So why is all this important? T.A. 2941 happens to be the same year The Hobbit: An Unexpected Journey takes place. It then makes sense that the events mentioned above are also playing their course. I expect Dol Guldur to play a much larger part in The Hobbit: The Desolation of Smaug. We may even get to see the attack of the White Council on Dol Guldur. However, do not get your hopes up, because I may be wrong.
I do have reason to believe, though, that Bolg, and possibly Azog, are tied up in all this also. Why? Because of a remarkable similarity between several pictures. Do you notice the doorway behind Bolg? It is clearly the same style of architecture, with the rust, inward pointing spikes, as the entrance to Dol Guldur (above and to the left) and the doorway behind Gandalf as he is fighting Thrain (to the right). Also, the stairs behind Bolg are very similar to the stairs surrounding Gandalf (to the left). Unless I am grievously mistaken, all these depict the same place. This brings up many more questions, such as how Bolg is involved with Dol Guldur. What he did in the book was lead the army of goblins and wargs in the Battle of Five Armies. There was no mention of him in relation to Dol Guldur. He came from Mount Gundabad, which, although it once a dwarven city (and the place where Durin the Deathless awoke), was then an orc stronghold. The occupation of Mount Gundabad is actually the origin of the hatred between dwarves and orcs, but that is a very long story for another time. Though, now that I think about it, Bolg would have had to pass through Mirkwood to reach the Lonely Mountain, so maybe he came into contact with Dol Guldur after all. However, it is still a total mystery concerning how all this will play out. We will just have to wait and see.