Inlaid marble

One note, the architecture (walls, columns, ceilings, exteriors, etc) of the Taj Mahal are decorated with the pattern you see below. These are not painted in. They are stones (jade, lapis lazuli, agate, black onyx and others) that were inlaid in such a way that they feel smooth to the touch and have lasted (with the exception of looting) for about four hundred years. If you click on this picture, you can see the details in detail. These are not marble tiles, but single huge pieces. The government has been more careful about people stealing the inlaid stones and the vast majority are still intact. This example was right in front of me on one of the exterior walls of the Taj.