The Ezana Stone
This tablet, situated in a field and well below today's ground surface, is believed to have been erected some time during the first half of the fourth century of the current era by King Ezana of Axum in what is now called Ethiopia.
The monument is interesting for several reasons. First, it is one of the few ancient written records to come from pre-Islamic Africa, Egypt being the other major source of inscriptions.
Second, the text on the Ezana Stone is written in several languages. If you Google this monument, you'll be told the monument is trilingual: Greek, which at the time was the lingua franca in many parts of the ancient world; Ge'ez, an ancient Ethiopian language that is still a liturgical language of the Ethiopian Orthodox Church and others, and Sabaean, an Old South Arabian language used in what is now Yemen and in parts of Eritrea and northern Ethiopia.
However, the actual facts are much more interesting than this. Please see the comment below from fellow flickerite YomArkegzi, who explains how the text is actually bilingual, something I wasn't aware of even though I visited the site with a guide and researched this monument on the Web after my return.
Third, unless I'm mistaken, the stone stands more or less where it was originally erected (or at least where it came to rest in antiquity), instead of gracing a hushed and elegant museum gallery in, say, Rome, Berlin or London, or, god forbid, a billionaire's private collection.
King Ezana ruled the Axumite Kingdom during the first half of the fourth century of the current era.
Ezana is known principally for having converted to Christianity, paving the way for the eventual Christianization of Ethiopia.
King Ezana also left his mark in the annals of history by invading the Kingdom of Kush in what is now southern Sudan. Sources differ on whether King Ezana conquered and put an end to the Kingdom of Kush, or merely inflicted damage that, along with other factors, led to the Kingdom of Kush's decline.
What does the tablet say, you ask? Well, I wasn't able to find a clear answer to that question. It appears King Ezana erected several "Ezana Stones" during his reign, including one in what is now southern Sudan.
My default answer would have been that the monument records King Ezana's conversion to Christianity and/or his victories over the Kushites, because that seems to be the consensus on the Internets.
However, I am grateful to viewer and contributor YomArkegzi, who explained the text "is actually on a campaign against the Beja in what is now NE Sudan that the inscription is about. There was a rebellion there which he suppressed; he relocated 4400 of the rebelling people and confiscated some of their cattle."