Inside the world's largest building

Step inside the world's largest building, where the sun shines 24-hours a day and visitors can go to the beach or go shopping or ice skating without ever stepping foot outdoor.

The New Century Global Center is now officially the largest freestanding building in the world.  Located in Chengdu, China, it has a staggering floor space of nearly 19 million square feet, and is so large it is capable of housing the equivalent of 20 Sydney Opera Houses and is almost three times the size of the Pentagon in Washington, D.C., according to News.Au.com.

But more amazing are the things you can find inside.

There is a faux Mediterranean village, a 14-screen IMAX Cineplex and an ice-skating rink large enough to hold international skating competitions.  There is also a huge water park called Paradise Island with an indoor "beach" -- and two five-star hotels.

Around 4.3 million square feet of the building are dedicated to shopping, and there's a Japanese-designed artificial sun that shines 24 hours a day, keeping the place warm and welcoming for visitors looking to escape the area's thick smog.

The complex, which opened last week, coincided with the expansion of a new subway line for the area and will be near a new airport set for completion in 2020.