Towers, yes. Well, there are towers and Towers, and then there are TOWERS.

Most castles have towers of one sort or another. The majority of these are mural towers, adding to the defensive weight of curtain walls. They can also be found lurking conspiratorially next to gateways.

Keeps, of whatever shape or form, can also be considered to be Towers. But bigger, stronger and more important than the mural variety.

Elcho Castle
[Elcho - Perth & Kinross]

TOWERS are a step beyond even this. In Scotland, they are several steps upward as well. Take an average domestic house, with cellars, kitchen, great hall, private apartments, chapel et al. In England and Wales these tend to spread out along the ground in a nice rambling sort of way. If you need to defend the place, you stick a curtain wall, and maybe a moat, around it and call it a "fortified manor-house". In Scotland (and in some other, less civilized parts), you take the whole thing and turn it on one end. Et voilą, you have a "Towerhouse". Go see Amisfield Tower, a few miles north of Dumfries, if you don't believe me.

I'm sure you've had the experience of running upstairs and immediately forgetting what it was that you went up there for. So you go back down and then remember. Live in a towerhouse and your memory improves dramatically. Either that or you get to be very fit indeed.

On the subject of towerhouses, Scottish variety, you may notice references to "Z-plan", "L-plan" etc. Here are some illustrations of these terms:

L-plan T-plan E-plan Z-plan

These designs are usually formed from a rectangular tower with extra bits added on, either at the time of building, or (more usually) at a later date. The additional wings may contain extra rooms or staircases.