1. Rhaetian Railway
   The Blue Train
2. The Rocky Mountaineer
   The Ghan

In 2008, a five-stop span running from Thusis, Switzerland to Tirano, Italy on the Rhaetian Railway became a UNESCO World Heritage site. The four-hour ride winds through tunnels and over valleys in the Alps and is one of the world's best.

1. Maasai Mara
   Kruger National Park
2. Serengeti
   Ngorongoro

Tanzania's Serengeti is one of the most famous and oldest ecosystems in the world, and today it's home to thousands of lions and millions of wildebeest. The word "Serengeti" means "endless plains" in the Maasai language.

1. Ancient city of Rome
   Ancient city of Jerusalem
2. Ancient city of Athens
   Ancient city of Damascus

It's nearly impossible to comprehend the list of occupants that lived in Damascus, but at different points, the city was home to the Canaanites, Babylonians, the Macedonian, Roman, Byzantine and Ottoman Empires, the current Syrian Arab Republic and more.

1. Carlsbad Caverns
   Jeita Grottoes
2. Gorham's Caves
   Mammoth Caves

This national park sits in New Mexico and consists of 119 limestone caves formed by rainwater millions of years ago. There are dozens of popular rooms within the caves, like the Hall of Giants and King's Palace., and the longest cave in the park is Lechuguilla Cave, which runs more than 140 miles.

1. Venice
   Florence
2. Milan
   Pisa

Tourists can expect to pay anywhere between €2 and €5 to enter Venice, and entry prices can rise as high as €10 during peak seasons. The fees help raise money for the city but also help curb overcrowding in the city of more than 250,000 residents.

1. Tahiti
   Galapagos Islands
2. Bora Bora
   Nantucket Island

The Galapagos Islands are famous for being the place where Charles Darwin carried out a lot of his studies to help him form his theory of evolution, and the area is home to an abundance of wildlife. You'll find everything from birds and lizards to penguins and turtles on the islands.

1. Kita
   Timbuktu
2. Gao
   Mopti

Timbuktu is a real place, and it's in the middle of Mali, which is in Africa. In the 13th century, it's said that Mali was the largest producer of gold in the world, so the emperor at that time, Mansa Musa, was the wealthiest person in the world, but there is no way to confirm that definitively.

1. Berlin Cathedral
   Aachen Cathedral
2. Basilica of St. John's the Baptist
   Cologne Cathedral

More than 20,000 people visit this German landmark every day, and it became a protected site in 1996. Construction began in the 13th century, but the building wasn't finished until 1880. It was bombed close to 100 times in WWII but is still standing.

1. Sumatra Rainforest
   Amazon Rainforest
2. Congo Rainforest
   The Everglades

The Amazon rainforest is the world's largest of its kind and is home to an unknown amount of wildlife. Almost 400 billion trees in the forest inhale carbon dioxide and exhale oxygen to balance the atmosphere. The Amazon produces more than 20% of Earth's oxygen.

1. Chauvet Cave
   Mammoth Cave
2. Cueva de las Manos
   Lascaux Cave

Cueva de las Manos sits in Argentina and holds some of the oldest works of art ever discovered on Earth. Probably the most famous artwork in the cave is the stenciled hands on the cave walls, and the last people to occupy the site left in the first century.

1. Great Barrier Reef
   Amazon Reef
2. Apo Reef
   Ningaloo Coast

Close to 3,000 reefs span more than 1,400 miles in the Coral Sea near Australia. Ocean life ranging from fungi to whales depend on the reef, and it's home to thousands of different species of animals. It's been a protected site since 1981, and preservation efforts have recently ramped up.

1. Longmen Grottoes
   Yungang Grottoes
2. Mogao Grottoes
   Yulin Grottoes

These limestone Buddhist structures can be found in China and range in size from one inch to almost 60 feet tall. The most popular cave rooms feature art from the 5th century, and hundreds of thousands of laborers worked on the sculptures.

1. The Capitol Building
   Independence Hall
2. Washington National Cathedral
   Supreme Court of the United States

This is the site where America's founding fathers debated and approved both the U.S. Constitution and Declaration of Independence and where they held congressional sessions between 1775 and 1783. It was originally the Pennsylvania State House.

1. Hong Kong
   Singapore
2. Monaco
   Vatican City

Vatican City is the smallest and least-populous country in the world but is home to the Pope and Catholic Church, making it one of the most powerful countries in the world. It's also home to some of the world's most iconic landmarks, which makes it one of the most visited countries in the world.

1. Palais Kinsky
   The Hofburg
2. Schonbrunn Palace
   Schloss Esterhazy

This palace located in Vienna was finished in the mid-1700s and was given to the last ruler of House of Habsburg, Empress Maria Theresa, as a wedding gift. One of the first parties she threw at the palace was to celebrate the first children in the country who received smallpox immunization.

1. Sichuan Giant Panda Sanctuaries
   Lone Pine Koala Sanctuary
2. Boon Lott's Sanctuary
   Sepilok Orangutan Sanctuary

This series of reserves and parks became a protected site in 2006 and is home to some of the world's most endangered mammals and thousands of plant species. You'll have to travel all the way to the middle of China if you want to visit.

1. Zion National Park
   The Sundarbans
2. Komodo National Park
   Maasai Mara National Reserve

On the islands of Indonesia, you can find this park that is home to the Komodo dragon, the largest lizard in the world. It can grow 10 feet long, weigh up to 200 pounds and run up to 12 mph. They hunt and eat mammals and might even have a venomous bite.

1. Mont-Saint-Michel
   Monaco
2. Singapore
   Macau

This French island features a monastery at the top, stores at the bottom and fishing and farming homes outside the city walls. Religious structures were built in the eighth century, and the island's location allowed it to survive through decades of wars.

1. Yellowstone National Park
   Everglades National Park
2. Grand Teton National Park
   Redwood National Park

The Everglades is home to a diverse array of wildlife ranging from manatees to panthers and is an incredibly unique ecosystem. It's the only tropical jungle on the contiguous U.S., and more than one million tourists visit the area each year.

1. Elephanta Caves
   Caves of Niaux
2. Fingal's Caves
   Gorham's Cave

This complex consists of five main caves as well as a few smaller locations that feature dozens or artworks dedicated to Hindu deities. The historic site dates back to the 2nd century B.C. and is said to have been completed in the mid-6th century.

1. Drottningholm Palace
   The Royal Palace
2. Haga Palace
   Rosersberg Palace

This palace became a designated site in 1991 and was built for the queen of Sweden in 1580. It burnt down the next century, was rebuilt in 1681 and has been a royal residence ever since. Today it's also one of the most popular tourist attractions in the country.

1. The White Cliffs of Dover
   Amalfi Coast
2. Big Sur
   Jurassic Coast

This coast on the English Channel gets its name from rock formations in the area that date back to the Jurassic era. The coast consists of fishing villages, cliffs, arches, bays and more, and became a designated site in 2001.

1. Angkor Wat
   Kedarnath Temple
2. Vaishno Devi
   Lotus Temple

This temple in Siem Reap is one of the most popular attractions in Southeast Asia and appears on Cambodia's national flag. It was dedicated to the Hindu god of truth and later became a Buddhist temple.

1. Old Town of Amsterdam
   Old City of Bern
2. Sibiu Old Town
   Warsaw Old Town

The Old City of Bern is home to quite a few interesting and historic sites, including the Bern Minster, which is the country's tallest cathedral, and the Zytglogge, which houses one of Europe's most famous astronomical clocks. There are dozens of historic monuments within the city, and the entire old town is a heritage site itself.

1. Mammoth Cave
   Carlsbad Caverns
2. Fingal's Cave
   Lascaux Cave

This cave system crawls around Kentucky for more than 400 miles and is more than double the length of the next-longest cave system. You'll find plenty of limestone structures and a multitude of famous rooms, like the rotunda room and the bottomless pit, when exploring the system.

1. Jasper National Park
   Hawaii Volcanoes National Park
2. Los Glaciares National Park
   Zion National Park

Antarctica is one of the places on Earth everyone should visit, but it's not the easiest place to travel to. You can get a glimpse of what it might be like by traveling to the tip of Argentina and taking in the mammoth glaciers and crystal lakes at Los Glaciers National Park.

1. Buddhas of Bamyan
   Tian Tan Buddha
2. Gifu Great Buddha
   Leshan Giant Buddha

You will find giant Buddha structures all over Asia, and one of the coolest depictions is this 8th-century, 233-foot-tall cliff-face carving sitting on the Dadu River in China. You won't find a taller rock Buddha anywhere in the world, and it's the tallest ancient statue by far.

1. Old Town of Prague
   Vanalinn
2. Warsaw Old Town
   Historic Center of Naples

Prague's nickname is "City of a Hundred Spires," and the city one of the most picturesque in the world. Its old town is home to the oldest operational astronomical clock in the world, and the existence of the town dates back to the 9th century.

1. Trafalgar Square
   Times Square
2. Red Square
   Plaza Mayor

Moscow's Red Square is Russia's largest and most popular square and is home to famous landmarks like the fortified Kremlin complex, Saint Basil's Cathedral and Lenin's Mausoleum. It became a designated site in 1990 and is one of the world's most famous city squares.

1. Pompeii
   Valley of Temples
2. Leptis Magna
   Jericho

The Valle dei Templi spans more than 3,000 acres and is home to several Ancient Greek temples dating back to the 6th century B.C. It is one of the most significant sites in the world, and it sits in a country that is home to more heritage sites than anywhere else.

1. Cave of El Castillo
   Chauvet Cave
2. Lascaux Cave
   Cave of Altamira

More than 600 drawings and thousands of engravings dating back 17,000 years cover the walls of the Lascaux Cave in France. Many of the paintings were painted in color from yellow and black minerals found within rocks, and there are no landscape drawings on the wall.

1. The Sundarbans
   The Everglades
2. Tongass National Forest
   Mossy Forest

This system of forests, rivers and flats sits in the Bay of Bengal on the southern coast of Bangladesh and covers more than 2,300 square miles. The mangrove forests are the largest of their type in the world, and the area is home to a wide range of endangered animals.

1. Jericho
   The Acropolis
2. The Pantheon
   Delphi

You can't create a list of important world sites without including Greece, and alongside the Great Pyramid of Giza, the Acropolis is the most famous ancient site in the world. It is home to many historic structures, including the Parthenon.

1. Gorham's Cave
   Cave of Niaux
2. Jeita Grotto
   Fingal's Cave

These caves are located in Gibraltar and were first occupied 55,000 years ago. No fossil proof of Neanderthals has been unearthed at the location, but artifacts, tools and art have been found and carbon dated to the relevant times.

1. Triglav National Park
   Bavarian Forest National Park
2. Krka National Park
   Plitvice Lakes National Park

These lakes, waterfalls, canyons and valleys make up one of Croatia's largest and most popular national parks. More than a million tourists visit the site each year, and the park's 16 lakes vary in color from green to blue to grey, depending on different factors.

1. Stromboli
   Mount Etna
2. Mount St. Helens
   Mount Agung

Mount Etna is located on the island of Sicily and is the biggest active volcano in Italy. Its first recorded eruptions occurred thousands of years ago, and it may have been active for more than two and a half million years. It has erupted once a year since 2001, making it one of the world's most active.

1. Wulingyuan
   Black Forest
2. Bandipur National Park
   Tongass National Forest

Wulingyuan gained fame when it inspired the scenery for the multi-million dollar blockbuster "Avatar," and its mini-forests sitting atop sandstone pillars are some of the most unique land formations on the planet. The area consists of four national parks, including Zhangjiajie Park.

1. Naples
   Rome
2. Milan
   Athens

The old center of Naples has been a heritage site since 1995, and the city has close to 3,000 years of history. The ruins of Pompeii and the Amalfi Coast are just minutes away, but the city's greatest contribution to Earth is pizza Margherita, which was invented in the city.

1. Pyrenees
   Andes
2. Himalayas
   Swiss Alps

The protected area of the Swiss Alps is called the Jungfrau-Aletsch and has been a UNESCO site since 2001. It's home to several mountains that rise more than 13,000 feet, and much of the land in the area is untouched.

1. Vredefort crater
   Nordlinger Ries
2. Chicxulub crater
   Sudbury Basin

It's estimated that more than 2 billion years ago an asteroid more than nine miles in diameter struck Earth, leaving a 190-mile-wide crater in what is today the country of South Africa. The Chixulub crater in Mexico was created from the asteroid that killed the dinosaurs.