It is estimated that as many as one hundred and fifty days out of the year were free from farm labor. Using the time off from farming, the Mayans built magnificent cities and temples to honor their many gods. In early Mayan history, homes were built with wattle-and-daub walls in an oval shape with a thatched roof of palmetto fronds. These homes stayed dry when it was raining, and cool when it was hot. They contained very little furniture, and were used only for eating and sleeping. Decedents of the Maya still continue to build and live in these huts today. The Mayans used stone to construct temples and pyramids. Some of their best creations include: the Caracol, an astronomical observatory in Chichen-Itza, the tomb of Lord Pacal, the royal palace, which was used to look out for invaders over the Usumacinta River, El Castillo, or the Pyramid of Quetzalcoatl, and the Temple of the Magician, which was rebuilt five times to follow the rounds of the Mayan calendar every fifty two years. The great architecture was only one of the many aspects that made the Maya such an advanced civilization. The Maya reached their height in the classic period (AD 300 to AD 900). Over one hundred cities existed during this time, and some of the most advanced included: Tikal, Uaxactun, Quirigua, Copan, Palenque, Uxmal, Kabah, Sayil, Labna, Etzna, Old Chichen, and Coba. All of these cities served as cultural, religious, and spiritual centers for the Mayan people and rulers. Culture was a very important aspect of Mayan life. The Mayans favorite way to express their pride and religious devotion was to build temples, pyramids, and buildings that would all form large cities. The Mayan workers who constructed these dwellings often decorated the walls with hieroglyphics that would tell anything from a person's life to an important religious belief or tale. Cities that flourished during the Classic period were located in current day Guatemala and were led by the large city of Tikal, which had many pyramid-temples that rose over two hundred feet high.