Paintings

Paintings are non-craftable decorative furniture items that can be placed on background Walls. Each is a framed image that depicts a particular scene, usually Terraria-related. Their tooltips generally contain a person's name, apparently intended to credit each painting's fictional artist.

There are currently 70 obtainable paintings, of which 14 are sold by the Painter under certain circumstances; 15 are found placed naturally in underground cabins, 22 in the Dungeon, and 13 in the Underworld; 5 are acquired from Goodie Bags; and 1 is awarded by the Angler for completing a quest.

From Painter
Paintings purchased from the Painter bear the tooltip "V. Costa Moura", apparently the artist's name.

Trivia
(V. Costa Moura > Costa Moura > Cost Mour > Cost more)
 * The paintings that are "attributed" to V. Costa Moura could mean that they are worth less than what they are sold for.
 * They could also be a reference to the fact that items are bought at 5x the sell price. (V = 5, Costa Moura stated above)