Masonry structures commonly exist in reality and still are popular all over the world. It has been reported and studied that these buildings are vulnerable to strong external loadings imposed by earthquake, strong wind, blastetc. In the past few decades, different seismic retrofitting and strengthening approaches for masonry structures/elements have been developed and implemented. In this paper, the previous studies on the strengthening/retrofitting techniques for Unreinforced Masonry (URM) buildings subjected to seismic and extreme loads are reviewed and summarized. The fundamental concept of strengthening/retrofitting approaches is to (i) reduce the influence of external loading, (ii) upgrade the individual element’s load-carrying capacity and (iii) improve the integrity of masonry structure. A comparison and assessment of the advantages and disadvantages of each method is presented to identify the most suitable method in different cases. It is expected that this paper will provide some helpful information and guidance for the engineers and householders in choosing an appropriate technique in strengthening/retrofitting URM structures.