Cemetery World

Novel, first published: Analog Science Fiction / Science Fact, Nov. 1972-Jan. 1973

Earth, abandoned and destroyed ten thousand years ago by nuclear war, has become a huge cemetery for humans from all over the galaxy. A greedy and powerful corporation, Cemetery, heads this galactic undertaking, strictly controlling the movements of any visitors. Over Cemetery's protests, the protagonist, artIst Fletcher Carson, to compose his chef d'oeuvre on the planet Earth must be able to travel freely. Carson is accompanied by Bronco, a sentient machine that collects data for his composition, Elmer, an ancient robot formerly a native of Earth and technician in the Final War, and Cynthia Lansing, an Earth historian seeking a buried treasure near the Ohio River.
Mounted on Bronco, they begin their quest, always looking over their shoulders for trouble from Cemetery. They join the local natives in a hoedown, and at the dance, Cemetery throws a bomb at Bronco. They also meet a mysterious robed figure who calls himself the census taker, and he, in turn, introduces them to the Shades, ghosts of people buried in Cemetery. Escaping from robot wolves and telepathic ghouls, they unearth Cemetery's secret operation - the company is smuggling valuable artifacts to Earth in the caskets.
To escape Cemetery, they allow the Shades to send them back in time, but they travel too far back. They meet the Raveners, sentient war machines composed of human and robot brains, who now want to serve humans, but the people left on Earth flee them in fear. They promise to meet the Raveners three thousand years in the future.
The company then goes forward in time and comes upon a museum. One of the Shades explains what has already happened in the future - if they will only go back in time and play out their roles by confronting Cemetery wIth evidence of its smuggling activities. They have been pawns in a plan by the census taker, an alien archeologist, to establish a museum containing the stolen artifacts. Cemetery will cooperate rather than face a scandal, and they have a trump card to enforce their cooperation - the Raveners.
After all the fun of the quest, the time-travel ending seems so contrived and elaborate, functioning only to nail an old familiar villain, the greedy corporation.

Ewald, Robert J.: When the Fires Burn High and the Wind is from the North, p.104-105