The Papal Basilica of Saint Peter

The Papal Basilica of Saint Peter (Basilica Sancti Petri), officially known in Italian as the Basilica Papale di San Pietro in Vaticano and commonly known as St. Peter's Basilica, is a Late Renaissance church located within the Vatican City. St. Peter's Basilica has the largest interior of any Christian church in the world, holding 60,000 people. It is regarded as one of the holiest Christian sites. It has been described as "holding a unique position in the Christian world" and as "the greatest of all churches of Christendom"

In Catholic tradition, the basilica is the burial site of its namesake Saint Peter, who was one of the twelve apostles of Jesus and, according to tradition, first Bishop of Rome and therefore first in the line of the papal succession.

The Great Wall of China

The Great Wall of China  is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups such as the Xiongnu from the north and rebuilt and maintained between the 5th century BC and the 16th century. Since the 5th century BC, several walls have been built that were referred to as the Great Wall. One of the most famous is the wall built between 220–206 BC by the first Emperor of China, Qin Shi Huang. Little of that wall remains; the majority of the existing wall was built during the Ming Dynasty.

The Great Wall stretches from Shanhaiguan in the east to Lop Nur in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. The most comprehensive archaeological survey, using advanced technologies, has recently concluded that the entire Great Wall, with all of its branches, stretches for 8,851.8 km (5,500.3 mi). This is made up of 6,259.6 km (3,889.5 mi) of sections of actual wall, 359.7 km (223.5 mi) of trenches and 2,232.5 km (1,387.2 mi) of natural defensive barriers such as hills and rivers.

It's the world's longest wall.

The Old City of Jerusalem

A mountainous walled city with a 5,000-year history, Jerusalem is sacred to the three great monotheistic religions of Judaism, Christianity and Islam - which means it is sacred to more than a third of the world's population. For Jews, Jerusalem is the site of the Temple, now in ruins except for the Western Wall; for Christians, it is the site of Christ's death and resurrection; for Muslims, it is the site of the Prophet's night journey to heaven. Jerusalem is therefore a major site of pilgrimage for all three religions as well as, unfortunately, a place of religio-political tension over this important piece of land. The city is also popular destination for non-religious travelers, thanks to its unmatched historical and spiritual importance, its network of museums and concerts, and the archeological treasures that are continually discovered here.

Today, the Old City is roughly divided into the Muslim Quarter, the Christian Quarter, the Jewish Quarter and the Armenian Quarter. Following the 1948 Arab-Israeli War the Old City found itself located entirely on the Jordanian side of the demarcation line. During the Six Day War in 1967, which saw hand to hand fighting on the Temple Mount, the Old City transferred to Israeli control.