Solomon and the Queen of Sheba
These are bizarre images in a bizarre story. Was the Queen of Sheba Black? (link) Was she Jewish? Consider the image below. King Solomon is greeting the Queen of Sheba, but Solomon looks like a medieval rabbi in gold and the Queen of Sheba and the court have strayed out of a medieval Italian pageant.
The painting is from an interesting and large series of frescoes by Piero della Francesca called The Legend of the True Cross, painted in a church in Arezzo in the 1450's. (One of the two main panels is at the bottom of this page.) In the legend, wood from the Garden of Eden survives through the centuries to become the cross on which Jesus will be crucified. In other panels the Jews (including Solomon) do their best to avoid blame for this by trying to hide or destroy the wood, which keyed into the anti-Semitic preaching of the time.
The image detail below, from the same frescoes, is interesting for similar reasons. This African figure is on a banner at a battle between the Byzantine Emperor Heraclius (the good guys) who are defeating the Persian Emperor Khosrow (the bad guys) for control of the sacred wood. Piero della Francesca has Jews and Moors (like this one) fighting for Khosrow, which is why the banner is torn as they go down to defeat.
As for the legend of the True Cross itself, it got its start, apparently, when St. Helena, the mother of Emperor Constantine, found it in Jerusalem some time before her death around 330 CE. She was quite prolific in finding sacred relics and building churches, and this may have been her crowning achievement. The story really took off with the publication of the Golden Legend (compiled 1259 to 1266), by Jacobus de Voragine, later the Archbishop of Genoa.
Nowadays the True Cross seems to exist in dozens of pieces, in Greece, Spain, Italy, France, Belgium, Ethiopia and so on. Even I have a bit.
Below is another extravagant 15th century interpretation - from a Basel church:
