However, there and at most big sights, you can bypass lines by reserving an entry time in advance on their websites. If your time is worth anything (and I always assume travelers have very valuable time), you should try to get advance reservations for any must-see sight that offers them — the Eiffel Tower, Neuschwanstein Castle in Bavaria, Anne Frank's house in Amsterdam, Barcelona's Picasso Museum, and so on. But be warned: Slots can fill up long in advance, especially in peak season, so it's smart to buy tickets as early as possible.

If you miss out on advance tickets, there's usually a creative (or pricey) way to avoid lines. At the Vatican Museums, booking a guided tour gets you right in (this works at other places too, such as Versailles or Rome's Colosseum). In Florence, an expensive but worthwhile sightseeing pass called the Firenze Card lets visitors bypass long lines at sights like the Uffizi Gallery (best collection of Italian paintings in the world) and the Accademia (Michelangelo's David). A similar pass in Paris lets you skip the ticket lines at the Louvre and Orsay museums, but does not cover the Eiffel Tower, where, if you're willing to climb the stairs, you can reduce your wait times.

Self-service ticket kiosks, like ones at the Louvre, Versailles, and Madrid's Prado, are becoming common — and can provide a faster way in. In St. Petersburg, I learned from a local guide that you can avoid ticket lines at the Hermitage museum by simply buying your tickets at the machines in the courtyard. With up to 10,000 cruise travelers a day flooding into the city — and the Hermitage the top sight on their lists — this place can be a zoo. But with my machine-bought ticket, I walked right by the ticket line and within minutes was enjoying the Leonardos, Rembrandts, and Matisses while imagining the ostentatious lifestyles of the czars who collected them.

For some sights, it's possible to buy tickets elsewhere (sometimes with a small booking fee). Same-day Vatican Museums tickets are often available at the tourist information office in St. Peter's Square or at the office of tour company Opera Romana Pellegrinaggi. In Venice, tickets to the line-ridden Doge's Palace also include entry to the never-busy Correr Museum, where it's much faster to buy a ticket. In Athens, entry to the Acropolis is covered by a combo-ticket that you can pick up at other, less-crowded sights, such as the Ancient Agora or Roman Forum.

Timing is important. Each sight tends to have certain days or hours when crowds are worst. In general, sights tend to be packed on weekends and free-entry days. Besides the weekend, Versailles and the Orsay are packed on Tuesdays because the Louvre is closed then. The Vatican Museums are mobbed on most mornings — except on Wednesdays, when people pack St. Peter's Square to attend the papal audience. In general, it's best to visit a sight first thing in the morning or late in the day — but not always. On my last Acropolis visit, I went around noon — perfect timing, as the cruise-ship crowds, who had arrived in the morning, were heading in the opposite direction.

Sometimes an itinerary doesn't allow for flexibility. At these times, you'll have to make the most of it. Recently I was forced to lumber through Versailles on one of the most crowded days of the year (a Sunday in July). It was an experience I'll never forget. A steady crush of visitors shuffled through the hot and muggy one-way route, as if enduring some horrible punishment. But the payoff here is the magnificent Hall of Mirrors. Even with a mossy carpet of tourist heads, sights like these are a thrill to see — and worth every sweaty second.

Rick Steves ( writes European travel guidebooks and hosts travel shows on public television and public radio. Email him at This email address is being protected from spambots. You need JavaScript enabled to view it. and follow his blog on Facebook.