Saint Peter's Basilica in Vatican City is one of the largest Christian churches in the world, begun in 1506 and took over 100 years to complete. It covers 5.7 acres and can hold over 60,000 people made of stone and marble. Many popes are buried there as it is believed the apostle Peter, to whom Jesus gave the keys of Heaven, is buried underneath the altar. The Shaolin Monastery in China is a Chan Buddhist temple built in 496 AD and famous for its combination of martial arts and Zen Buddhism teachings, allowing the storage of chi or spiritual energy believed to surround all organisms.