altar at the eastern end to face the sunrise. Gravestones, too, are aligned west-east. To find direction from a mosque, you need to go inside and look for the niche in one wall, which indicates the direction for prayer. This niche, known as al-Qibla, will be the direction of Mecca, wherever you are in the world. And synagogues normally place the Torah Ark at the eastern end, positioned so worshippers face towards Jerusalem. (Synagogues in countries east of Israel will face west.) 3. Weathering " Start Quote The prevailing winds carry rain and pollution. These then hit the buildings, leaving patterns. The wind comes from the southwest in the UK more often than from any other direction. This results in asymmetrical weathering patterns on buildings - similar to the erosion seen in nature . Look up, above the cleaned glass and metals of the lower floors, to the natural stone or weathered bricks higher up. Notice how the building's corners all show subtly different weathering patterns. The contrast between southwest and northeast corners is the greatest. But the shifts in colours, where the rain and pollutants have left their mark, can be read on all sides with a little practice. Trees, too, indicate direction, with the very tops combed over by the prevailing wind. 4. Flow of people Rush hour crowds point the way Pacific navigators learned to follow the birds in their search of land. They quickly realised that while an individual bird can behave eccentrically, a pair -