I have now seen a fair few German houses and noticed a big difference with UK houses: the German ones always have cellars. [Remember that this is merely a log of my observations – your mileage may vary – and is thus not a scientific study.]
New houses in the UK don’t, by and large, have a cellar. The builder puts in foundations and builds from there. I have been in old houses (maybe one hundred or more years old) and these do, but typically modern ones do not.
In contrast, it seems pretty much all houses in Germany have cellars, including the new ones being build as I speak. What is more, they are typically used as proper living spaces because they tend to be lighter and more airy than their UK counterparts.
Let me generalise.
In the UK, the ground floor is at ground level. If there is a cellar, it is below this, which means, of course, no opportunity for natural light (or fresh air). Furthermore, because digging down is hard work (meaning expensive), the ceiling height of these cellars tends to be slightly on the low side.
In Germany (I have seen similar in France and Belgium), the ground floor of a house is about a meter above ground. Yes, this means to enter the house you must always climb a few steps to get to the front door. But the cellar can therefore have windows around it (facing onto ground level) that can let in natural light and fresh air. The Germans often use their cellar as extra living space: it is not unusual to see cinemas, offices, bedrooms, bathrooms, saunas, wine stores, and even swimming pools situated in the cellar (alongside more mundane necessities such as boilers and washing machines).
Usually, continental summers are much hotter than UK ones and so this could simply be a necessary measure to enable the occupants to have an easy place to keep cool. But I do like the extra flexibility they offer.