Edinburgh

Edinburgh sits on an extinct volcano that erupted 350 million years ago. The city built its castle on top of one volcanic plug while Arthur's Seat, another volcanic remnant, looms 251 meters above the eastern skyline.

People carved homes into this dramatic geology as far back as 5000 BC.

The town's name comes from "Din Eidyn," a hillfort the Angles captured around 638 AD. They added "burh" (old English for fort) to create Edinburgh.

The Scots didn't reclaim it until 1018, when Malcolm II won the Battle of Carham. By 1437, after James I was murdered in Perth, Edinburgh became Scotland's official capital when Parliament started meeting there permanently.

Between 1740 and 1790, Edinburgh became a city packed with geniuses. The Scottish Enlightenment produced philosopher David Hume, economist Adam Smith (whose "Wealth of Nations" has never been out of print since 1776), geologist James Hutton, and architect Robert Adam.

A visitor said he could stand at the Mercat Cross on the Royal Mile and shake hands with 50 brilliant minds in minutes. Voltaire wrote, "We look to Scotland for all our standards of civilization."

All this brainpower from a nation of barely one million people.

But centuries earlier, Edinburgh had a different kind of problem: too many people, not enough space. The Old Town's solution? Build up, not out.

Ten and eleven-story buildings became typical in the 1500s, with one reaching 14 stories. The rich lived on upper floors while the poor crowded into basements.

Residents shouted "Gardyloo!" (watch out for the water!) before chucking their bathroom waste out the window into the street below.

Gross? Absolutely. The stench earned Edinburgh the nickname "Auld Reekie" (Old Smoky) because you could see and smell the smoke and filth from 20 miles away.

Climb Arthur's Seat for 360-degree views, or walk the Salisbury Crags where James Hutton figured out how rocks actually work. Tour Edinburgh Castle, which has been a fortress, royal palace, military base, and prison since the 12th century.

Walk the Royal Mile from the castle down to Holyrood Palace, stopping at St Giles' Cathedral. Check out the New Town's fancy Georgian buildings from the 1700s.

Try haggis (sheep's heart, liver, and lungs mixed with oatmeal and spices) served with neeps (mashed turnips) and tatties (mashed potatoes). It sounds weird but tastes way better than it sounds. Find it with whisky sauce at pubs along the Royal Mile, or grab some at The Haggis Box.

Parents can tour the Scotch Whisky Experience near the castle, which has 3,000 bottles on display.