The earliest Buddhist art did not show the Buddha at all. Buddha was clear that he was not a God to be idolized. Rather, he was a person who was able to disidentify from his limited persona and this is was made him free.
Early Buddhist art showed a leaf from the forest where Buddha meditated, or a footprint, but never Buddha the person. In later centuries, Buddha appears in Buddhist art. In some later forms of Mahayana Buddhism, whole pantheons of Buddhists appear.
Now Buddhist temples and monasteries have either one Buddha on the main altar, or, as in the case of Tibetan Temples, many Buddhas, emanations of Buddhas and Buddhist protectors all around.
If you go to Bangkok, a river cruise takes you to the site of the above Buddha-Tree. For more about the tree and Buddha: The Story--The Tree
For those interested in learning about Buddhas in Buddhist art, there are many resources. Here, I list a few of the best!
TibetanArt.org The rare Yak hair thankga and the Tibetan Tooth Extractor
HimalayanArt.org From the Rubin Foundation. Mainly Tibetan.
ExoticIndiaArt.com An article about the evolution of the Buddha Image in art
Greco-Buddhist Art Article on the first 1st Century BC anthropomorphic representations of Buddha. A complete history of Buddha Art with timeline and photos. Recommended.
For those needing an Asian Art Appraiser:
Michael Cohn Gallery (In NYC)
Corpright BuddhaArt.com 2007-9