Uranus

A jet of methane that burst out of the cloud and froze before it could fall. The column leans with the wind, the spray hangs above it in rings, and the drops that never reached the cloud still hang in the air in arcs. The topmost drop glows.

A storehouse for things that had to stay cold, built where nothing ever thaws. Two rows of capsules stand inside under their indicator lights; the frost has crept in through the east wall and one corner is under a ridge of ice. Two of the capsules are open, and one of them was not opened from outside.

A cone of methane ice boulders stacked one on another, with a column of three hailstones on top. Diamond hail sets into the crust of the boulders after every rain, and the largest stone of all glows in the column. The hailstones around it lie in a streak downwind.

An expedition came to Uranus for diamonds: here they fall from the sky as hail. They froze a citadel into a drifting berg of methane ice and cut four tiers into it: barracks and stores under the hail funnels, a cryovault, the rinks and cells, and the lower halls under the throne room. The cold paid them back in its own coin. The hail they poured under the throne hall settled over one long winter into a master, a giant of ice crowned with hailstones; the crew froze where they sat, and something in the vault thawed.

A survey probe that froze in flight. It was diving nose first through the calm band when the methane set around it in a single lump, and the lump came down on the cloud with the probe inside. The stern sticks out, the beacon still burns, and the ice has cracked open along the hull.

The same ring as on Earth, on a dais of the local stone and in the colors of this world: whoever set the gates out did it on every world at once. This one sleeps. It answers only one who has brought down the master of this world and lived through its trial; then lay the master's heart, the dust of the road and what this world gives into the ring, and it will join the other gates that are awake.

A platform on legs above the cloud, with three habitat modules around a hub and a mast that still carries a light. It answers no call. Haze has swallowed the west half and the module that stands in it; the shuttle pad is empty, and nobody saw the shuttle leave.

Two pressure ridges of methane ice with an arch of packed ice sprung between them. Nobody built it: the frost grew it in one cold night, the way it grows everything here. A third of the span has come down since. The keystone glows, and the barrel on the far ridge was left by someone who crossed before it fell.

An observatory tower that fell on its side and lies where it fell, dome and all. The planet rolls on its side too, and whoever built here should have expected it. The foundation is still there; the refractor inside has been set back on its pier by someone who came after.