This exceptionally large and elaborate Gothic cathedral on the main square of Milan is one of the most famous buildings in Europe. It is the world's third largest church. Impressive is both its dazzling white facade as well as the more than 2,000 sculptures inside.

Anyone visiting the National Mall in Washington D.C. in the capital of the United States will definitely pass by the Lincoln Memorial Reflecting Pool. Over 3.6 million people visit the memorial annually. It is also known as the setting for Martin Luther King's "I Have a Dream" speech.

The Alhambra in Granada, Spain, is a masterpiece of Moorish architecture. Originally built for military purposes, it was named a UNESCO World Heritage Site in 1984. It is one of Europe's most popular tourist attractions.

The spectacular, multi-colored Church of the Savior on Blood in St. Petersburg in Russia dazzles with its golden domes and intricate mosaics. It was built on the site where Emperor Alexander II was assassinated in March 1881.

The Mosque-Cathedral of Córdoba is regarded as one of the most accomplished monuments combining Moorish and Christian architecture. Originally constructed from the 8th century onwards as the Great Mosque of Córdoba, the Islamic holy building was converted into a Christian cathedral in the 13th century.

The white marble mausoleum Taj Mahal in Agra, which was completed in 1643, is regarded as a prime example of Mughal architecture. Its name was inspired by Mumtaz Mahal, Mughal emperor Shah Jahan's beloved wife, who died while giving birth to their 14th child.

Every day some 20,000 pilgrims visit the St. Peter's Basilica in Italy's Vatican City. Built atop of an earlier 4th century church, it was completed in 1626 after 150 years of construction. The cathedral boasts many masterpieces, including Michelangelo's Pietà, his soaring dome, and Bernini's 29 meter-high baldachin over the papal altar.

Angkor Wat is one of Southeast Asia's most important religious sites. Originally dedicated to the Hindu god Vishnu, it has remained a place of worship since its founding during the Khmer Empire in the 12th century.

A stellar example of Mughal architecture, the Sheikh Zayed Grand Mosque is considered to be one of the key places of worship in Abu Dhabi. Its interior dazzles with millions of Swarovski crystals. The mosque, which took over 10 years to complete, accommodates over 41,000 worshipers, making it currently the largest mosque in the United Arab Emirates.

And finally here is the site that has won the 2016 Trip Advisor must-see landmark ranking: Machu Picchu, Peru's famous lost city in the Andes Mountains. This 15th-century Inca site, located 2,430 meters (7,970 ft) above sea level, is renowned worldwide for its dry-stone walls, which were built without the use of mortar, making these incredible buildings as mesmerizing as they are mysterious.