Denver International Airport is coming to life and about to receive the first arrivals today. By midnight, more than 1,500 aircrafts would’ve touched down here, delivering tens of thousands of people to this modern metropolis. But when did people first come to the plains?

It's not so long ago in the life story of the continent, just 13,000 years since this was a virgin territory. And back then, different giants cruised the landscape. Imagine if we could travel back in time and see these plains as they were then, emerging from the grip of the last great ice age, an area of pristine wilderness, stretching for one and a half million square miles, untouched by man and brimming with extraordinary animals.

But 13,000 years ago, an even more extraordinary animal arrived. What if we could follow in the footsteps of these first hunters as they entered the unknown and staked their claim to these vast spaces? What would this wild new world have looked like through their eyes? And what strange creatures would they have encountered here on the American Serengeti?

1 metropolis

n.首府;大城市

参考例句：

Shanghai is a metropolis in China.上海是中国的大都市。

He was dazzled by the gaiety and splendour of the metropolis.大都市的花花世界使他感到眼花缭乱。

2 virgin

n.处女，未婚女子;adj.未经使用的;未经开发的

参考例句：

Have you ever been to a virgin forest?你去过原始森林吗?

There are vast expanses of virgin land in the remote regions.在边远地区有大片大片未开垦的土地。

3 pristine

adj.原来的，古时的，原始的，纯净的，无垢的

参考例句：

He wiped his fingers on his pristine handkerchief.他用他那块洁净的手帕擦手指。

He wasn't about to blemish that pristine record.他本不想去玷污那清白的过去。

4 wilderness

n.杳无人烟的一片陆地、水等，荒漠

参考例句：

She drove the herd of cattle through the wilderness.她赶着牛群穿过荒野。

Education in the wilderness is not a matter of monetary means.荒凉地区的教育不是钱财问题。