The view you may admire if you look up entering the great hall of the Galeria Borghese.  I will not speculate on its size, but the fresco is for sure more than 100 meters big.

Galeria Borghese is an art museum located within the Villa Borghese Pinciana in Rome (Italy). It is one of the most renowned museums in Rome and houses an extraordinary collection of artworks from various periods. The gallery was originally established by Cardinal Scipione Borghese, a nephew of Pope Paul V, and a prominent art collector, and patron of the arts, in the 17th century. He amassed an extensive collection of sculptures, paintings, and antiquities, which he displayed in his private residence, the Villa Borghese. The collection was later transformed into a public museum in 1903.

The Villa does not look very impressive from the outside. However, besides the numerous pieces of art, which can be admired inside, the villa is a real eye-catcher in itself with its richly decorated interiors with among others colorful frescos.

The central hall fresco, as you can see on the close-ups below, is a very detailed one. How great work this is I realized only after I processed the random made photos back home.

Frescoes were a common technique used to decorate ceilings and walls in Rome, in ancient times as well as during the Renaissance. It was adopted in many other places and countries usually in churches, palaces, and villas belonging to the rich. The technique was also applied in China and India. The true fresco technique involves painting with a water-color on the wet plaster. If the painter did not manage to put color onto the plaster before it dried up, the plaster had to be removed and put on once again. Frescoes were also painted with a technique called fresco secco, where the painting was applied on dry plaster. (Secco stands in Italian for dry, fresco – for fresh). The significant difference between a true fresco and the fresco secco is its durability. In the case of a true fresco during the drying process, the color becomes part of the plastered wall, and this way the fresco painting may preserve longer. Authentic frescoes are not suitable as a painting technique for countries where the climate is wet and cold.