According to Vitruvius, the town of Mytilene on Lesbos was elegantly built and magnificent in its appearance. Yet for its inhabitants, it was not a particularly good place to live:In that community when the wind is south, the people fall ill; when it is northwest, it sets them coughing; with a north wind they do indeed recover but cannot stand about in the alleys (plataeae) and streets (angiportus), owing to the severe cold.(Vitr. De arch. 1.6.1; translation: Morgan 1914)The architect explains what has gone wrong: the orientation of the street grid had not been adapted to the prevailing wind regimes, so that the Mytileneans unduly suffered from cold and sickness. In designing the urban street network, Vitruvius emphasizes, prevailing winds need to be kept as much as possible out of the narrower streets-the angiportus-where many houses had their main entrance. Later on, in his discussion of domestic architecture, Vitruvius returns to the issue of climate and weather, pointing out that differences between houses in different parts of the world stem from differences in climatological conditions. Hence, houses in Egypt are bound to differ from those in Hispania, and those in Pontus will be designed according to other priorities than those in Rome: aliter Aegypto, aliter Hispania, non eodem modo Ponto, dissimiliter Romae (Vitr. De arch. 6.1.1). For Vitruvius, urban development was, more than anything else, about designing the right city for the right environment and, thus, about limiting the extent to which adverse conditions could complicate urban life: the very location of the city, the layout and orientation of the street grid, the placement and design of the most important civic buildings, all were to be adapted to the natural environment in which the city was to be situated. Much of his advice is well known: cities should be built on higher ground, and they were not to be situated near marshes, unless these could be (and were) drained (De arch. 1.4.1); the forum should be situated right in the middle of the city, unless the city was a port, in which case it was to be situated close to the harbour (1.7.1); bath buildings were to be situated in the warmest possible location