A World Heritage Site is a landmark or area that is legally protected by an international convention and is administered by the United Nations Educational, Scientific, and Cultural Organization, also known as UNESCO. They were developed to highlight and protect the world's best and most distinctive sites. There are various heritage sites around the world. 
They may represent a noteworthy human achievement and serve as proof of our intellectual past on the planet, or they may be a site of outstanding natural or cultural beauty. 

Here given are the top 7:

1. Taj Mahal, India: This beautiful monument is located in Agra, India, and is composed of flawless ivory marble. It is an excellent work of art to enjoy. It is unquestionably one of the most popular UNESCO World Heritage sites, and it is on practically everyone's travel bucket list. This stunning edifice, made completely of white marble, appears to gleam in the moonlight, and the sight of the sparkling Yamuna river just across the way will leave you in awe. 

2. Christ the Redeemer, Rio de Janeiro: This prominent structure in the middle of Rio de Janeiro, Brazil, provides a spectacular vista when experienced in person. This UNESCO World Heritage landmark stands 130 feet tall, with arms that measure 28 meters wide.

3. Colosseum, Rome: The Colosseum in Rome is one of the world's most iconic structures, and visitors to Italy should undoubtedly visit it. It is well-known for being the largest amphitheatre ever built and has managed to keep that status to this day. This structure is notable for its use of concrete and sand rather than rock or metal.

4. Chichen Itza, Mexico: This magnificent city is set in Mexico's stunning Yucatan Peninsula and has justifiably earned the title of a Wonder of the Modern World due to the enormous volume of visitors. According to sources, this is by far the most visited Mayan site. The Maya civilization built this site between the 9th and 12th centuries, and it attracts a large number of visitors in the autumn and spring.

5. Machu Picchu, Peru: A vacation to Peru is incomplete without visiting Machu Picchu, a UNESCO World Heritage Site. It's amazing how well the Incas planned and built their land. According to historians, it was erected as a residence for the Inca monarch Pachactui around 1450, but its existence was unknown until 1911, when it was shown to the world.

6. The Great Wall of China: This construction requires no introduction! As a result, it has rightfully earned the status of UNESCO World Heritage Site. It is undoubtedly a wonder and sight to behold, as are the engineering accomplishments required to build it. During the Ming Dynasty, it was the world's greatest military fortress, spanning over 6000 square kilometers. 

7. Petra, Jordan: Nestled in southern Jordan, this location is an archeological treasure trove. This location is partly carved out of limestone, while the other half is erected. As you pass through the famed gateway, the Siq, you will be greeted by numerous tombs and homes.