In any city, in any country, go to any mental institution or halfway house you can get yourself to. When you reach the front desk, ask to visit someone who calls himself "The Holder of Madness". The worker will bow formally, with his hand tucked under his chest, and motion for you to follow into a waiting room. He will leave, and the lights will go out. When they return, thirteen seconds later, you will be in a dirty hallway with cuneiform scratching on the walls.
As you walk, the scratches will gradually change, to resemble an alien writing; attempting to decipher the writing will send you into writhing agony for the rest of your mortal days. As you reach a black orb, shimmering with liquidity, you must speak, "We are all mad, for you are the bringer." If the Orb comes to resemble a doorway, enter. If the Orb begins to rotate, you will be dragged into the nether.
In the following chamber, made of twisting black coral, stands a figure, ever-changing. In him, her, it, you will see all men, all women, children, animals, creatures, beasts, horrors that exist. It will not recognize your presence, unless you extend your left hand and say, "I swear an oath to Koth; may the Tower ever stand." At that time, he will cease his changing, long enough to place his hand on yours, and your soul will be torn out of your body and placed within a numbered humanoid skull resting on a pile to his left.
Touching that skull will bring you to the foyer of an ancient temple, lying in the sands of Mesopotamia.
The skull is Object 61 of 538. It must converge once more.