Europe

The largest amphitheatre ever built, once flooded for mock naval battles in front of fifty thousand spectators.

A Nasrid palace-fortress where water, light and geometry were engineered into one continuous piece of architecture.

Bluestones hauled 250 km from Wales and set to frame the midsummer sunrise and midwinter sunset.

Sits under the auroral oval, so the sky performs on any clear dark night through the polar winter.

Sixteen terraced lakes whose travertine dams are still being built, millimetre by millimetre, by moss and algae.

Meltwater tunnels under Europe's largest ice cap, refrozen each winter into blue glass that never repeats.

Polar bears outnumber people, the sun does not set from April to August, and a seed vault sits inside a mountain.

A city on 118 islands, built on millions of alder piles driven into the lagoon mud.

Its astronomical clock has been tracking the sun, moon and zodiac since 1410 and still runs.

The Eiffel Tower was meant to be dismantled after twenty years; it survived because it made a useful radio mast.

For a few weeks each summer the sun barely sets and the whole city stays out through the white nights.

The rim of a volcanic caldera that blew apart around 1600 BCE in one of the largest eruptions in human history.

Eighteen basalt islands in the North Atlantic where sheep outnumber people and the weather changes by the hour.

The longest railway line in the world — 9,289 km, eight time zones and about a week from Moscow to the Pacific.

Monasteries on sandstone pillars, once reachable only by rope ladders that the monks pulled up behind them.