A、To build their tombs. B、To help them to find life after death. C、To remind the world of them permanently. D、To reach the sky.

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 in Egypt, kings built the pyramids. [26] They used to build them as their 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. [27] The oldest pyramids that we know today are the pyramids near Sahara in Egypt. They are about 5,000 years old. There are many pyramids along the Nile River. [27] The largest is the pyramid of Khufu. It is made of two million three hundred thousand huge stones, most of them higher than a person. [27] It is about 144 meters high. [27] To build the pyramid of Khufu 100, 000 men worked for 20 years. We know there was wonderful treasure in the pyramids. Robbers went into the pyramids and took many of these treasures. Today some of the treasures are in museums.
    The people of Mexico also built pyramids.  They did not build the pyramids for tombs. [28] They built pyramids and then built temples on top of them. Each pyramid has a wide stairway that goes from the bottom to the top. There’s nothing inside the pyramids, only dirt or more stones.