system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How were the domes of historical structures, such as the Taj Mahal, constructed using heavy materials such as stone/bricks and without modern techniques of reinforcement using steel bars ?

How were stable structures made using stone/bricks for the construction of the domes of historical structures such as the Taj Mahal without using modern techniques of reinforcement using steel bars ?
gpt
Steel reinforcement bars are used to improve the strength of concrete and other materials in *tension* (pulling, rather than pushing or squeezing). The main reason that domes and arches are so popular in structures built from stone or brick is that all the forces in those shapes are in compression, which stone has a much easier time withstanding even without steel reinforcement.