Paris

Paris needs 4 days: the Eiffel Tower and the Louvre on one, Notre-Dame and the Latin Quarter on another, Montmartre on the third, and Versailles as an excursion on the fourth. April-June avoids humid summer heat and the massive July-August crowds. It's expensive, among Europe's priciest capitals, though efficient public transport helps control daily spending. It's the world's most visited city, and the Louvre, with over 35,000 works on display from a collection of nearly 500,000, is the largest and most visited art museum on the planet.