The next in our Spotter's Guide series reveals 120 of the world's great human constructions and where to find them, from cloud-piercing skyscrapers and ancient sites to classic buildings and contemporary designs. Packed with facts, maps and photos, it's a fun and fascinating introduction to the sublime, the strange and everything in between. When we travel it's often to see a building - the Taj Mahal, the Leaning Tower of Pisa, the Eiffel Tower. They're things of beauty, symbols of their age and emblems of human endeavour. Sometimes, buildings are the reason we decide to go somewhere; think of an icon such as Bilbao's Guggenheim and Cambodia's Angkor Wat temple complex. Other times, buildings help make a visit more enriching and rewarding, like discovering the old district of Pelourinho in Salvador, Brazil and the majestic HagiaSophia in Istanbul, Turkey.