The answer is simple but impractical: Grossly overbuild the structure, so that it is lightly stressed. Don't use any reinforcing material within the concrete (

The answer is simple but impractical: Grossly overbuild the structure, so that it is lightly stressed. Don't use any reinforcing material within the concrete (much of the damage that happens to a modern reinforced concrete structure is the result of the internal reinforcement swelling due to corrosion). Ensure that the structure doesn't freeze (water that penetrates the concrete and freezes will cause cracking). Note that following these limitations would rule out the vast majority of modern concrete structures.