다음 글에서 콜로세움의 구조를 가장 잘 나타낸 문장을 고르시오.
Rome was like a giant museum to me. ①We began our sightseeing at the Colosseum. ②Nowadays, we can only see a part of what was once the greatest structure in the ancient world. ③It amazed me to think that people could build such a structure without modern construction equipment. ④The Colosseum has eighty arches through which about fifty thousand people could go in and out in fifteen minutes! ⑤As I reached the top of the stairs inside, I looked down and I could almost hear the cheer of the crowd.