
The ubiquity of the "at symbol" (also called the "snail" by Italians and the "monkey" in Slavic languages) would makes us think it's a 20th century phenomenon.
But we would be wrong. In fact, a recently discovered letter by a Florentine merchant named Francesco Lapi used the symbol @ in a letter written exactly 473 years ago, on May 4, 1536.
Amazing!