Mars

Spheres of hematite scattered over the plain, from pebbles to boulders, weathering out of the low ledge to the north. The crews called them blueberries: blue-gray outside, rust all the way through. The largest one is hollow.

A natural arch of banded rock, nine blocks across. The wind cut it out of a single ridge, sanding the soft dark layers away faster than the pale ones; the hematite at its feet is what fell out. It has stood for a million years and will stand a while yet.

A flat-topped hill with two hollows, a ridge and a groove on its summit. From the ground it is a mesa; from above, at the right hour, it is a face looking at the sky. The journal records it as a trick of shadow. The journal has not seen it at dawn.

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.

Eight crystals of fire opal standing in a ring on a rampart of rock, none the same height, all leaning a little outward. In the pit at the center there is nothing but a barrel. At night the ring glows brighter than opal should.

A derrick on the polar cap, fourteen blocks of pole and trim over a shaft cut into dry ice. The crew drilled for water and brought up cores of frozen carbon dioxide and perchlorate salt, barrel after barrel. The bit is still hanging where they left it.

A six-wheeled rover that drove up to a dark dune and stopped. The front axle sank, the nose dipped and a wheel came off when the crew tried to reverse out. The tracks behind it are still sharp: nothing on Mars erases them but the storms.

A garrison was told to hold the bastion on the canyon rim until relief came, and relief never came. The storm broke the tower, so they cut downward from its foot: casemates, a vault for the seeds of Earth, then a prison and a throne hall for a commander who had crowned himself. The scorpions came up through the lower casemates, and the thing that led them has been sitting on the throne ever since.

A hall inside a hill, behind an airlock door and a corridor: racks of sealed barrels, hydroponic beds still green under the lamps, and seed from every farm on Earth, laid down in case. The vault was meant to wait for people; its keeper still waits on the charging pad between the racks, and the niche with the seeds of Earth is sealed. The south-east corner of the vault has sagged; the lamps have not gone out.

A relay on a six-block crag, reached by a stair cut into the south face: a mast with a dish, a shack of station panels, a lamp still burning. It listened for Earth as long as there was someone to listen. The grotto under the north face is occupied now.

A brick vault half-buried by the dune that was meant to shelter it. A crew sat out a dust storm here, sleeping on stone ledges by lantern light; when the wind dropped they walked on and left the bread. Something has since dug itself into the drift: there is a funnel in the sand before the door, and the door is sealed.

A pillar of banded rock sixteen blocks high, the last of a plateau the wind took away. The soft dark layers are eaten back and the hard ones hang over them in ledges. Something glints on top: fire opal, bright enough to steer by at night.