A city to last ten million years: Construction

In the future, a high-tech human civilization has colonised a distant planet. The planet is basically Earthlike in gravity, climate, terrain and vegetation. They want to build Forevertown: A city with low-tech construction which is built to last.

The projected lifespan of Forevertown is measured in millions of years. To start off with, the inhabitants will have high technology; but the city should remain habitable if they regress to Iron Age or (possibly) Stone Age levels. For the sake of argument, assume the city will not be deliberately destroyed by human action.

The technology of the city builders is highly advanced but not "magical" by our standards. They can't violate the laws of physics as we currently understand them; in particular, magic self-repairing materials are not an option over this timescale.

What is the best way to build Forevertown? More specifically:

What form of construction would be most durable, with least maintenance? Mortarless stone buildings as seen in Machu Picchu are an obvious candidate, but I am open to other suggestions.

Related questions:

What is the best location for Forevertown?

What are key maintenance issues for Forevertown?

Edit: Mind-boggling though these timescales may be, the Earth is projected to remain habitable for about 1 billion years. If there are still humans then, and they haven't fallen victim to the Singularity / zombie apocalypse / demolition of Earth for hyperspace bypass, they will have to confront similar issues over the very long term.

posted about 9 years ago

Royal Canadian Bandit‭

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