Back in 1980, BMW’s engineers had an idea. What if they built a bike that could handle rough off-road terrain just as well as long highway stretches and twisty back roads — to their eyes, a sort of ? That bike was the R80 G/S, its Gelände/Straße name referring to both the overland and street sides of its personality.

Now, 43 years later, BMW has built its millionth boxer-twin GS (no longer divided by a slash) model. The bike has changed just a little from its initial iteration — the 800cc airhead replaced with a 1250cc water-cooled variable-valve-timed boxer twin, the frame geometry tweaked and adjusted for modern construction, and of course the addition of the famed — but the core idea of “one bike for everything” remains intact.

Many will fault the full-bore GS for its size, claiming it’s simply too heavy to take on the kinds of off-road adventures that earned the GS badge its pedigree, and that may be fair — the current bike weighs 549 pounds with a full tank of gas — but there’s no denying it’s been incredibly important to the world of motorcycling.

The flat-twin GS kickstarted the adventure game, bringing to life the truest expression of “” you’ll ever find on two wheels. It led to not only BMW’s adventure lineup (of which I’ve owned two) but the entire modern ADV market. All your Tigers, your Teneres, your KTM Adventures, and your Africa Twins can trace their lineage back to that first R80 G/S.

But what comes next for the boxer GS, after 43 years and a million units? Well, it seems we’ll have to wait until later this year to find out.