Some clematis prefer west facing so your corner could be a good location for a hardy variety - they will benefit from the warmth of the house wall. How far North/South are you in Denmark - hardiness might be the limiting factor. There is a question (posted 5 April) from Scotkat asking about hardy clematis.

The house is about 45km North of Copenhagen, about 10km South of Helsingør, on the East coast of Sjælland island, in a place called Espergærde. My wife and I were at the local garden centre today, they had many Clematis there, of course, just because they sell them doesn't make them suitable... At my house in Southern England, I had several Clematis, including one, (macropetala I think), that went absolutely crazy and completely covered the front of the house. I was thinking of regular jackmanii types for the trellis's. I'll try to find the question you mention.

Of course, plants other than Clematis might suit the location better, but I have no experience with such beasts.

The macropetalas are native of Siberia so could very well suit your current location. I guess you have a quite tricky climate, so you'd probably be best asking the garden centre's advice.

Have a look at a variety called "Warsaw Nike." It has purple flowers, and was bred in Poland to cope with their cold winters.

Cheers folks. I've looked at pictures of the Warsaw Nike, looks good, I'd been thinking of The President, as I guess that is my favourite, and also Josephine for contrast, although I could not see that one at the garden centre when we were there over the weekend. I ordered the trellis sets this morning, so with the usual delays may be able to get the project going next week.