Short answers, pulled from the story.
Roman art is the art of Ancient Rome and the territories of its Republic and later Empire, including architecture, painting, sculpture, and mosaic work. Luxury objects in metalwork, gem engraving, ivory carving, and glass are sometimes considered minor forms, though they were not regarded as such at the time. Sculpture was perhaps considered the highest form of art by Romans, with figure painting also highly regarded.
Roman art relied heavily on Greek models while also drawing on Etruscan, native Italic, and even Egyptian visual culture, making it a highly creative pastiche. Much Greek sculpture known today survives only as Roman marble copies. By the 2nd century BC most sculptors working in Rome were Greek, often enslaved in conquests such as that of Corinth in 146 BC.
Very little Roman painting remains, and the surviving range covers only about 200 years out of roughly 900 years of Roman history. The best known pocket is the wall paintings of Pompeii and Herculaneum, preserved by the eruption of Mount Vesuvius in AD 79. Panel painting on wood, the most prestigious form besides sculpture, largely perished because wood is a perishable material.
Trajan's Column is the foremost example of Roman historical relief, recording the various Dacian wars conducted by Trajan in what is now modern Romania. It presents over 650 feet of spiraling length with more than 2,500 realistically rendered individuals, plus landscapes, animals, and ships. It survived destruction by being adapted as a base for Christian sculpture.
Gold glass fixed a layer of gold leaf with a design between two fused layers of glass, and most of the roughly 500 survivals are roundels cut from the bottoms of wine cups, pressed into mortar to mark and decorate graves in the Catacombs of Rome. They predominantly date from the 4th and 5th centuries. Most are Christian, with many pagan and a few Jewish examples.
Roman architecture produced the greatest innovations of Roman art through the use of concrete, which allowed massive buildings like the Pantheon and the Colosseum that earlier materials could not. The Colosseum was completed around 80 AD and held over 50,000 spectators. The arch, concrete, and the dome enabled vaulted ceilings, public baths, and aqueducts such as the Pont du Gard and the aqueduct of Segovia.