plaster - the demand for specialists
A fairly simple task would be to list dozens of professions, because the modern world is so developed that in recent years, a lot of ways to make money, and those created many years ago are still not time-barred. A good example of the latter case is the stucco, plaster ornaments and so on the external walls and internal. A person specializing in this field should have a broad knowledge in the field of construction machinery, as well as sculptural art, because the stucco was based on these two areas. To create a solid stucco are necessary exceptional manual dexterity and patience, so surely this is not a job for every man.
A little bit of theory
At their simplest, moldings are a means of applying light- and dark-shaded stripes to a structural objects without having to change the material or apply pigments. The contrast of dark and light areas gives definition to the object.
Imagine the vertical surface of a wall lit by sunlight at an angle of about 45 degrees above the wall. Adding a small overhanging horizontal molding to the surface of the wall will introduce a dark horizontal shadow below the molding, which in consequence is called a fillet molding. Adding a vertical fillet to a horizontal surface will create a light vertical shadow. Graded shadows are possible by using moldings in different shapes: the concave cavetto molding produces a horizontal shadow that is darker at the top and lighter at the bottom; an ovolo (convex) molding makes a shadow that is lighter at the top and darker at the bottom. Other varieties of concave molding are the scotia and congé and other convex moldings the echinus, the torus and the astragal.
Placing an ovolo directly above a cavetto forms a smooth s-shaped curve with vertical ends that is called an ogee or cyma reversa molding. Its shadow appears as a band light at the top and bottom but dark in the interior. Similarly, a cavetto above an ovolo forms an s with horizontal ends, called a cyma or cyma recta. Its shadow shows two dark bands with a light interior.
Źródło: https://en.wikipedia.org/wiki/Molding_(decorative)#Theory
Facts from Wikipedia
Ceilings have frequently been decorated with fresco painting, mosaic tiles and other surface treatments. While hard to execute (at least in place) a decorated ceiling has the advantage that it is largely protected from damage by fingers and dust. In the past, however, this was more than compensated for by the damage from smoke from candles or a fireplace. Many historic buildings have celebrated ceilings. Perhaps the most famous is the Sistine Chapel ceiling by Michelangelo.
Ceiling height may have psychological impacts
Źródło: https://en.wikipedia.org/wiki/Ceiling#Elements