Beyond the answers - interesting background to this quiz

A city older than most empires

Baghdad was founded in 762 as the capital of the Abbasid caliphate, laid out as a great round city on the Tigris. It soon became one of the largest and most learned cities in the world, home to the House of Wisdom, where scholars translated Greek, Persian and Indian works into Arabic. The city's name is commonly understood to mean "given by God" in Persian.

When an empire ended in a single day

The fall of Constantinople in 1453 marked the end of the Byzantine Empire, the eastern half of the Roman Empire that had outlasted Rome itself by nearly a thousand years. Ottoman forces under Sultan Mehmed II breached the city's famous land walls, which had resisted attackers for centuries. Many Greek scholars fled west afterwards, carrying manuscripts that helped fuel the Renaissance.

Two very different mountain ranges

The Appalachians and the Rockies are often mentioned in the same breath, but they are geological strangers. The Appalachians began forming hundreds of millions of years ago and have been worn down into rounded, forested ridges. The Rockies are far younger, still rising and sharp-edged, which is why they look so dramatically different on a map or from a plane window.

The disease behind a global health emergency

Tuberculosis primarily attacks the lungs, though it can spread to other organs. Caused by the bacterium Mycobacterium tuberculosis, it has been found in human remains thousands of years old and was once known as consumption. The disease remains a major global health concern, and the World Health Organization has long treated it as a leading infectious killer worldwide.

The bird that outsizes all others

The ostrich is the largest living bird, standing up to about 2.7 metres tall and weighing well over 100 kilograms. It cannot fly, but its long legs make it one of the fastest runners on two feet. Its closest living relatives include the emu and the cassowary, all members of a group of flightless birds called ratites.