The Ark is evocative of the Ark of the Covenant, which contained the tablets with the Ten Commandments engraved on them. This is the most holy place in a synagogue, comparable to the Holy of Holies. Engraved onto the walls and the ceiling are illustrations depicting aspects of Jewish law. The ark is made of wood, usually oak, but sometimes pine or chestnut. In ancient times, the temple priests would burn every seventh year as an offering to God. The wood from these burned trees was used to make new arks for the temple. It is estimated that there are still over 100 standing synagogues in Europe that were built using wood from these burned trees. There are several features of a synagogue's interior that are important for worshipers to see. These include the bimah, or platform, where religious leaders deliver speeches during services; the ark, where Torah scrolls are kept before they are read from the front of the room; and the mechitza, or barrier between men and women, which prevents sexual harassment by allowing people to focus exclusively on their prayers. Synagogues also have features that are important for worshipers to feel. For example, the ark and bimah are often raised up on pillars so that people can pray from their seats. There are also benches for men and women to sit separately.