The document discusses different types of lintels and arches used in building construction. It describes lintels as horizontal structural members placed across openings to support the structure above. Various lintel materials include timber, stone, brick, reinforced brick, steel, and reinforced concrete. Arches are structures that span openings and support weight below through arch action. Key arch types include flat, semi-circular, segmental, relieving, parabolic, and others defined by their geometric shape. Arches are classified based on materials like brick, stone, concrete, metal and wood. Factors in arch construction and methods to prevent arch failure are also summarized.