This final year project deals with strengthening of masonry arches and vaults. Strengthening of existing masonry buildings is a topic that is being researched all over the world with the aim of extending the design working life and preserving historical buildings and monuments. At present, researches are mostly dealing with methods that use steel, carbon or glass fibers in FRP (fiber- reinforced polymers) and TRM (textile-reinforced mortar) systems, as well as steel ties or other fibrous materials that can be used as strengthening material for masonry arches. First, a brief overview of various techniques for strengthening of arches and vaulted structures and a comparison of their effectiveness is given. It is then followed by an experimental research conducted on scaled pointed arch models made of timber. Tests were carried out on unreinforced models and on models with reinforcement at the extrados or at the intrados of the arch, loaded with a pointed force at quarter span. It is shown that the collapse mechanisms of models reinforced at the extrados or at the intrados differ from models without reinforcement. In addition, shaking table tests were also conducted as well as tilt tests, as a simplified replacement method for dynamic testing. Finally, a numerical analysis was carried out, where using the principle of virtual work the limit value of the loading at which the arch turns into a mechanism was determined.