Illustration of 2 travelers pointing in a direction.
"But DNS told us it was this way."

Frequently Asked Questions

Why 8 destinations?

You can visit the Seven Wonders of the World, and whichever you consider to be the Eighth Wonder!

What are the Seven Wonders?


  • Great Pyramid of Giza
  • Hanging Gardens of Babylon
  • Statue of Zeus at Olympia
  • Temple of Artemis at Ephesus
  • Mausoleum at Halicarnassus
  • Colossus of Rhodes
  • Lighthouse of Alexandria


  • The Great Wall of China
  • Petra, an ancient city in Jordan
  • Christ the Redeemer, a statue of Jesus in Rio de Janeiro
  • Machu Picchu, an Incan site near Cuzco, Peru
  • Chichén Itzá, a Mayan city on the Yucatán Peninsula in Mexico
  • The Colosseum, an ampitheater in Rome, Italy
  • Taj Mahal, a mausoleum complex in Agra, India

What are some candidates for the Eighth Wonder?

  • Angkor Wat
  • The Leaning Tower of Pisa
  • The Moai Statues on Easter Island
  • The Empire State Building
  • The Palm Islands of Dubai
  • Niagara Falls
  • The Grand Canyon
  • The Terra Cotta Army of China
  • The Panama Canal
  • Compound interest

How do you calculate the distance between two airports?

Given two pairs of latitude and longitude, we calculate the great-circle distance using the haversine formula.

How do you calculate the shortest flight path?

This is an example of the Traveling Salesman Problem (TSP), which asks:

"Given a list of cities and the distances between each pair of cities, what is the shortest possible route that visits each city exactly once and returns to the origin city?"

Eight Wonders implements the Held-Karp dynammic programming algorithm to find an exact solution to the TSP. Every time the Itinerary Page is refreshed, this algorithm is executed to sort the destinations.

The TSP can also be solved using a naive approach by considering all possible travel paths and choosing the shortest one. However, this is slow and would be impractical if we had more airports.

A faster but non-exact solution involves choosing a starting airport and sorting the longitudes of the remaining ones. This could be inaccurate if we have three airports close in longitude, but the middle one is much farther south or north.

Ruby implementations for all three approaches are available on Github. Comments and corrections are welcome. Heuristic and approximation algorithms were not explored, and may be needed if we increase the number of destinations.

Can I actually book a plane ticket for my itinerary?

Round-the-world tickets are limited to flights served by airlines within a single alliance. Therefore it's unlikely your itinerary is purchaseable as a single ticket, unless you specifically choose airports that meet the requirements. The airport data is from OurAirports and has been filtered down to 8,802 airports with IATA codes. Since not all of these are major airports served by many carriers, a random selection of them will probably not meet the requirements.

For more information about round-the-world tickets, visit the three major airline alliances:

Some requirements for round-the-world ticket itineraries include the following, which are not enforced by the Eight Wonders planning tool:

  • A maximum total travel distance
  • Must continue in the same direction (eastward or westward)
  • A maximum number of stopovers
  • A maximum number of flight segments
  • Some backtracking may be allowed
  • Required to return to origin

Can I redeem airline miles for a round-the-world flight?

Yes, some airlines will let you book round-the-world tickets (within their alliance) with miles. Probably the best and most flexible option is ANA Mileage Club (Star Alliance), transferrable from Amex Membership Rewards.

Is my itinerary private?

Itineraries are accessible (and deletable) by anyone you share the 8-character itinerary code with. We generate a new code using Nano ID each time you create a new itinerary or copy an existing one. It's possible for a malicious party to generate codes until they find a valid itinerary code. At this time we do not plan to offer password protection for itineraries.

Will my itinerary be saved when I leave the website?

All itineraries are stored in our database until you decide to delete them. Every itinerary modification is immediately saved when it is performed. We do not plan to offer user accounts for managing multiple itineraries. Please make a copy of any codes you want to keep. If you forgot, please review your browser history.