When Mr Cerdà was designing Barcelona's Eixample, he must have thought that there was too much of a right angle and so he cut diagonal cuts here and there in the form of avenues: Diagonal, Meridiana, Sarrià, Gaudí, Roma and - perhaps the best of them all - Mistral.
Because if you are going to live next to an avenue, it better be quiet in terms of traffic. With some terraces to enjoy the good weather but without the space being too saturated. With local shops and traditional bars. And if it is hidden from the tourist crowds, so much the better. And if you want to add a comfortable seat, a drink of your choice, a sunny veranda, and you have the perfect combo for wasting (or investing) hours looking at the avenue.