This document discusses different types of lintels and arches used in construction. It describes 6 types of lintels based on materials - timber, stone, brick, reinforced brick, steel, and reinforced cement concrete. It then explains key elements of arches like abutments, piers, intrados, extrados, etc. Arches are classified based on materials, shape, and number of centers. Common shapes include flat, segmental, semi-circular, relieving, and dutch arches. Arches can be one centered, two centered, and up to five centered. Failure of arches can occur due to crushing, sliding of voussoirs, or uneven settlement.