The intricacy of the marble carving on the Taj Mahal is astonishing. It's hardly surprising that this building took 20,000 artisans to build over a 22-year period.
From the outside, the building gives the effect of tracery carving, but in fact it is mostly semi-translucent marble inlaid with semi-precious stones (lapis, carnelian, onyx, malachite, etc.) in beautiful patterns. Only four families did the inlay work on the Taj, using patterns and designs exclusive to each family. Two of the families are still doing this work today.
The effect of the light on the Taj Mahal is quite incredible, as you can see from the two photos below, which are of the same panel in different lights.
The carved stone lattice panels make changing patterns on the carved surfaces throughout the day as the light changes: