Delhi, the capital of India, offers a treasure trove of many sacred groves, water bodies, structures, and precincts that are of historic, aesthetic, architectural, and cultural significance. Efforts have been made mostly to preserve the architectural concepts of the Mughal era, but Delhi has many splendid monuments of the Sultanate era, which need exigent restoration and repair from getting faded into oblivion. Sadly, only the Qutb complex and Nizamuddin Dargah have received much attention from both government and non- government organisations, but other structures have been left unattended. It is also evident that every monument cannot be given due importance, and scores of capital cannot be utilized for their maintenance, but science and technology can offer alternate methods to restore and repair damages to these lesser-known monuments, which can also be considered in the long- term interest of the society from economic, cultural, and environmental viewpoints. This review is an attempt to delve into the architectural marvels of the Delhi Sultanate period, the cause of their deterioration, and the means of their conservation by the use of biotechnological tools, that is, use of essential oils, nanotechnology, and bio-mineralization as an effective, low-cost, eco friendly option to be adapted for future restoration and conservation of our heritage culture.