Failure and non-performance of infra-structural Systems are inevitable occurrences in countries, where the range of these systems is quite wide from traditional/heritage ones to modern ones in different areas. Understanding the causes and diagnostics of failure are continuing exercises where new inputs and dimensions are exhibited in each and every case. This is the basis and scope of the book where the mechanics, causes and types of failure of structures are discussed first followed by diagnostic and status assessment methodologies. The presentations are from micro-material level- to meso-system level and cover different systems from simple beams, columns and foundations to residential, commercial, landmark and traditional structures. Recent concepts like forensics, smart materials, sensors and visual information processing are also presented to meet the evolving technology trends. Case studies of practical systems augment and emphasize the importance of the contents presented in the book. The book will be of use in many levels ranging from a text book to a reference book on R&D to better understanding of mechanism of structural failures.