The Taj Mahal, built in Agra by the Mughal emperor Shah Jahan for his wife Mumtaz Mahal, is a mausoleum; its architectural power comes from the union of flawless symmetry with structural refinements.

The building is set on a raised marble plinth in perfect bilateral symmetry: the four sides of the central tomb are identical, four minarets rise at the four corners, and the long reflecting pool in front completes the symmetry vertically by mirroring the building in water. The char-bagh (fourfold) garden carries this axis into the landscape.

The structural heart is the central onion-shaped dome, which is also a double shell — the tall outer shell that gives the grand silhouette is separate from the lower inner one, so the exterior look and the interior scale can be designed independently. The surfaces are decorated by setting semi-precious stones (carnelian, jade, lapis) into recesses cut in the marble — the pietra dura technique; the ornament is not paint but the stone itself, and so does not fade. The subtlest detail is the minarets: the four are built not perfectly vertical but canted slightly outward. This both makes them look upright in perspective and ensures that, in a possible earthquake, the minarets would topple outward rather than onto the central tomb. The Taj Mahal thus unites symmetry, the double-shell dome, and a calculated structural foresight in a single marble composition.