Decay is inevitable by law of nature. As construction engineers, what we can do is to delay the process of decay. The restoration of old buildings represents an ecologically and economically valuable contribution to the quality of life. The aim of Architectural conservation is to prolong the life of buildings & the built environment of historic cities so that the future generation can enjoy them profitably. The crucial problem of construction is to raise the publicâ„¢s consciousness of the value of our heritage before it is lost forever and there lies the importance of the topic.Monuments include historic building from sophisticated architecture to the humble vernacular cottage. Indeed, legally, one stone on top of another may be deemed a monument if it is significant. Old buildings preserve the local culture and identity and create a sense of belonging. In a way, we recycle embodied human resource energy along with material energy. We bring alive the past to be a part of the future, creating important connections through time. When a building of historic merit is preserved or restored for adaptive reuse, its cultural energy is also "recycled." By contrast, adaptive reuse is much more labour-intensive than new construction, because it involves the reconditioning the existing structures to adapt to modern day requirements. The built heritage of the past civilizations has offered a wealth of information about our ancestors. Be it the Pyramids of Egypt, or the Colosseum in Rome, the Leaning Tower of Pisa, the Empire State Building in New York, or the more recently built Guggenheim Museum in Bilbao, these will go down in history as the heritage of our times. These buildings are the milestones, which lead backwards into the history of our world. The object of restoration is to revive the original concept or legibility of the structure. Restoration is based upon respect for original material, archaeological evidence, original design and authentic documents. Replacement of missing parts should integrate harmoniously with the whole but on close observation could be distinguishable. Restoration by using original material is justified, provided it is supported by firm archaeological evidence. For example cleaning of a building, replacement of missing elements etc are various forms of restoration.