From Sidar Ikbal Ali Shah's 'Afghanistan of the Afghans' 

Source: Afghanland.com:  There was a brave man named Farhad, who loved a Princess named Shirin, but the Princess did not love him. Farhad tried in cain to gain access to the love-cell of Shirin's heart, but no one would dare betray the fact that a stonecutter loved a lady of royal blood. Farhad, in despair, would go to the mountains and spend whole days without food, playing on his flute sweet music in praise of Shirin. At last people thought  to devise a plan to acquaint the Princess of the stone-cutter's love. She saw him once, and love which lived in his bosom also began to breathe in hers. But she dared not a mean laborer aspire to win the hand of a princess? It was not long, however, before the Shah himself heard some rumor of this extraordinary exchange of sentiment. He was naturally indignant at the discovery, but as he had no child other then Shirin, and Shirin was also pining away with love, he proposed to his daughter that her lover, being of common birth, must accomplish a task such as no man may be able to do, and then, and only then, might he be recommended to his favor. 
The task which he skillfully suggested was that Shirin should ask her lover to dig a canal in the rocky land among the hills. The canal must be six lances in width and three lances deep and forty miles long! 

The Princess had to convey her father's decision to Farhad, who forthwith shouldered his spade and started off to the hills to commence the gigantic task. He worked hard and broke the stones for years. He would start his work early in the morning when it was yet dark and never ceased from his labor till, owing to darkness, no man could see one yard on each side. 

Shirin secretly visited him and watched the hard working Farhad sleeping with his taysha(spade) under his head, his body stretched on the bed of stones. She noticed, with all the pride of a lover, that he cut her figure in the rocks at each six yards and she would sigh and return without his knowing. 

Farhad worked for years and cut his canal; all was in readiness but his task was not yet finished, for he had to dig a well in the rocky beds of the mountains. He was half- way through, and would probably have completed it, when the Shah consulted his courtiers and sought their advice. He is artifice had failed. Farhad had not perished in the attempt, and if all the conditions were in the attempt, and if all the conditions were in the attempt, and if all the conditions were fulfilled as they promised to be soon, his daughter must go to him in marriage. The Viziers suggested that an old woman should be set to Farhad to tell him that Shirin was dead; then, perhaps, Farhad would become disheartened and leave off the work. 

It was an ignoble trick, but it promised success and the Shah agreed to try it. So an old woman went to Farhad and wept and cried till words choked her; the stone-cutter asked her the cause of her bereavement. 

"I weep for a deceased," she said, "and for you." "For a deceased and for me?" asked the surprised Farhad. "And how do you explain it?" 

"Well, by brave man," said the pretender sobbingly, "you have worked so well, and for such a long time, too, but you have labored in vain, for the object of you devotion is dead!" 

"What!" cried the bewildered man, "Shinin dead?"

Such was his grief that he cut his head with the sharp taysha(spade) and died under the carved streamed into his canal was his own blood. When Shirin heard this she fled in great sorrow to the mountains where lay her wronged lover; it is said that she inflicted a wound in her own head at the precise spot where Farhad had struck himself, and with the same sharp edge of the spade which was stained with her lover's gore. No water ever flows into the canal, but two lovers are entombed in one and the same grave. 

Source:Afghanland.com: There is an old well some miles form Kabul called Chah-i-Rustam (Chah, well) of about the radius of five yards, and a network of iron is placed just under the water. The construction is of red stones, such as cannot be seen in the neighboring hills.

Rustam is the Afghan-Irani equivalent of Hercules, the great champion of the Arians, the prince of the land of Seistan. He fought the White Dragon and struggled for two whole days with Prince Isfandiar, in the epics. Seistan is on Western Afghanistan, named formerly Sakastan: Land of the Saka people.

Water is never drawn from the well, which is of a deep grey color. The well has no date on it, and on the walls big iron chains hang down to the surface. The legend goes on to say that Rustam, the great wrestler of Seistan, after being killed was thrown into the well, and a friend of his fixed these chains, so that Rustam's spirit might climb up and escape; but the enemies of the Rustam placed a net below the level of the water, and thus the dead hero of Firdowsi's classic, was forever lost.