Building Sets are the plain DUPLO brick sets, buckets and boxes of bricks without a story. DUPLO started in 1969, and the name comes from the Latin word for double, because each brick is twice as long, wide and high as a LEGO brick. The studs are made to fit, so DUPLO and LEGO bricks lock together and a builder can move from one to the other. For years the plastic bucket was the usual way to sell them, from the 1980s through the early 2000s, often shaped or printed as an animal, a farm or a circus, and some came as anniversary editions. Later sets switched to cardboard brick boxes with ideas for what to build on the side.
1975 LEGO Sets
1975 expanded Basic Building Sets and introduced more systematic, idea-led boxes. Proto-minifigures—small, faceless figures with single-piece legs—appeared in town and train sets, foreshadowing the 1978 minifigure. LEGOLAND-branded sets emphasized construction vehicles and realistic machinery, reinforcing everyday play before the arrival of dedicated Space and Castle themes.