Some of the most interesting buildings in the world are the pyramids. The pyramids stand huge and silent, and in modern days, people look at them and wonder, “Who built them? Why? When? What is inside? How did they do it?”
Thousands of years ago, certain kings of Egypt built the pyramids. They used to build them as tombs. The kings thought the pyramids would help them find life after death. They also wanted the world to remember them as important people. Some pyramids were for queens, but they are less interesting because they are not as big as those of the kings!
The oldest pyramid that we know today is the pyramid near Sakara in Egypt. It is about 5000 years old.
There are many pyramids along the Nile River. The largest is the pyramid of Khufu. It is made of 2,300,000 huge stones, most of them taller than a person. It is about 144 meters high. Inside the pyramid are the burial rooms for the king and queen and long passage ways to these rooms. The rest of the pyramid is made of solid stones.
Workers usually built the pyramids when they had little or no work to do on their farms. To build the pyramid of Khufu, 100,000 men worked for twenty years.
We know there are wonderful treasures in the pyramids. Robbers have dug into some of the pyramids and taken many of these treasures. However, today some of the treasures are in museums.
How did the people of ancient days build the pyramids? How did they carry and lift upwards the huge stones? Each stone fits in with one another so well though they didn’t have our modern machine at all! The ancient art work of Egypt give us the idea of a miracle. Scientists have studied the pyramids, but nobody can say just how they did it.

Which of the following is true？（）