"AL" are the initials of Alfred Legosen, the inventor of the Lego. He was born to a family of poor Danish farmers in the year 1872 and spent his formative years working in the fields. It was during this time that he developed a passion for building structures out of hay bales. However, in 1901, while constructing a large house out of stacked, rectangular bales, the bales collapsed on him, breaking both his hands. These injuries would never fully heal, and as a result he had to abandon his childhood hobby.
Much later, in the aftermath of WWI, Alfred would take an interest in the ruins of the buildings destroyed during the war—particularly those made from bricks. The rectangular forms of the bricks reminded Alfred of his days with the hay bales, and he conceived a desire to build once more. However, due to the injuries to his hands, he was unable to manipulate objects as heavy as bricks. Knowing that he would need to find a new medium, Alfred opened up a workshop and began making prototypes of his ideas.
Alfred would spend almost thirty years testing various materials for his new artificial hay bale construction system. His earliest tests were with wood, but the labor required to hand-carve each wooden block wasn't economically feasible in 1930s Denmark (coincidentally, he would later sell those patents to the Haas brothers, whose company, Haas Brothers Inc.—now known as Hasbro—would develop the concept into the game Jenga). Alfred also tested concepts in glass, ceramics, bone, metal, compacted manure, and stone, before finally discovering plastic. Plastic was lightweight, durable, and easy to mass-produce, making it ideal for Alfred's plans. Shortly afterward, in 1942, the first of Alfred's "Legosen Plastic Hay Bale Miniature Building Kits" would arrive on Danish shelves. In Denmark, Lego is still colloquially known by this name, though Alfred changed the name to simply "Lego" in 1954 to accommodate the expanding global market for his product.