Were the tower to be laid down across the plain of Shinar, it would be two days' journey to walk from one end to the other. While the tower stands, it takes a full month and a half to climb from its base to its summit, if a man walks unburdened. But few men climb the tower with empty hands; the pace of most men is slowed by the cart of bricks that they pull behind them. Four months pass between the day a brick is loaded onto a cart, and the day it is taken off to form a part of the tower.

Hillalum had spent all his life in Elam, and knew Babylon only as a buyer of Elam's copper. The copper ingots were carried on boats that traveled down the Karun to the Lower Sea, headed for the Euphrates. Hillalum and the other miners traveled overland, alongside a merchant's caravan of loaded onagers. They walked along a dusty path leading down from the plateau, across the plains, to the green fields sectioned by canals and dikes.

None of them had seen the tower before. It became visible when they were still leagues away: a line as thin as a strand of flax, wavering in the shimmering air, rising up from the crust of mud that was Babylon itself. As they drew closer, the crust grew into the mighty city walls, but all they saw was the tower. When they did lower their gazes to the level of the river-plain, they saw the marks the tower had made outside the city: the Euphrates itself now flowed at the bottom of a wide, sunken bed, dug to provide clay for bricks. To the south of the city could be seen rows upon rows of kilns, no longer burning.

As they approached the city gates, the tower appeared more massive than anything Hillalum had ever imagined: a single column that must have been as large around as an entire temple, yet rising so high that it shrank into invisibility. All of them walked with their heads tilted back, squinting in the sun.

Hillalum's friend Nanni prodded him with an elbow, awe-struck. "We're to climb that? To the top?"

"Going up to dig. It seems... unnatural."

The miners reached the central gate in the western wall, where another caravan was leaving. While they crowded forward into the narrow strip of shade provided by the wall, their foreman Beli shouted to the gatekeepers who stood atop the gate towers. "We are the miners summoned from the land of Elam."

The gatekeepers were delighted. One called back, "You are the ones who are to dig through the vault of heaven?"

"We are."