The Isfahan Shah Mosque is the building in which Safavid architecture masterfully solves two separate problems — uniting a tall outer silhouette with a well-proportioned interior in the same dome, and making a building part of a city square.

The mosque's key structural invention is the double-shell dome. Inside there is a lower inner dome that preserves the proportion of the space; outside there is a much taller, bulbous outer dome that dominates the city's skyline. Between them lies an empty air gap and connecting supports; the designer thus achieves a monumental height outside without disturbing the human scale within. The outer dome is sheathed top to bottom in turquoise and lapis glazed tile — the tile is not mere ornament but a skin protecting the mud-brick core from sun and rain; geometric and vegetal patterns dematerialise the surface in the light.

The plan follows the four-iwan Iranian mosque typology (an iwan being a vaulted hall open on one side): a giant arched iwan at the middle of each of the courtyard's four sides binds the space to its axes. The cleverest aspect of the mosque is urban: its portal opens onto Naqsh-e Jahan Square, but because the qibla direction is oblique to the square, the building is skilfully rotated behind the portal to obey both the square's geometry and Mecca at once. The Shah Mosque is the high point of Iranian-Islamic architecture, uniting the double-shell dome, the tile skin, and the iwan plan in a single urban composition.