Reconstruction is a set of technical procedures aimed at restoring the monument, damaged to a large extent as a result of mechanical processes (warfare, fire-, collapse due to old age) or advanced wear of structural elements, its original form and architectural features. The reconstruction process may concern both architectural elements, coming from different periods or only some epochs of the monument's existence, and structural elements of the building.
Depending on the scope of construction works, the reconstruction of a historic building may be complete or limited to only a partial state.
Full reconstruction is most often undertaken due to the need to bring the monument to a state of full usability, and also in these cases, when the destroyed object or group of objects has a special historical significance, when it is closely related to certain facts of major cultural importance or when it is justified by the need to preserve it, in a specific environment and surroundings, character of architecture corresponding to a given historical epoch or maintaining compositional balance.
The reconstruction of monuments is a particularly difficult type of technical and conservation work, especially when it must take into account the characteristic values of the work of different times. Therefore, reconstruction work is undertaken in these cases, when reliable historical documentation is available or parts of the monument are preserved in nature in their original form.
In essence, the reconstruction of monuments goes beyond the framework of theoretical conservation assumptions. In some cases, however, it is the only way to convey the characteristic forms and spatial assumptions of architecture. An example may be the rebuilt historic downtown of Warsaw, Gdansk, Poznań and others, whose form, not material reality, has an eloquent and moving effect.
The problem of rebuilding damaged monuments is particularly complex. The very fact of undertaking such an action raises serious doubts among art history theoreticians. they consider, that reconstruction can replace the lost object only in shape and form, but it cannot restore its individual originality and authenticity, at least because of it, construction and finishing works carried out by modern specialists, even technically and aesthetically perfect, they do not reflect the spirit of the creator, no traces of the craftsmanship of the past period.
Historical cataclysms in Poland, especially the last war, turned into ruins and ashes not only separate historic buildings, but also entire cities famous for their monuments and beauties. Hence, the rational reconstruction of destroyed monuments is considered a patriotic and social duty. The most important thing in the course of reconstruction is the separation of the original historic substance from this one, which needs to be supplemented. Taking into account historical and emotional considerations, the reconstructed object should bear the characteristics of the original work. From the scientific point of view, however, all additions cannot take the form of an uncritical and perfected reconstruction.. The rebuilt object should be treated as a copy or a symbol of the monument and cannot represent a falsified document of art and history. Therefore, the rule applies, so that in the course of reconstruction, all original parts of the monument are emphasized, leaving also more valuable layers, the reconstructed elements were clearly demarcated. Reconstructive procedures can only take place in exceptional cases, if it is required to integrate the most important structural parts of the building or to restore uniformity and formal continuity to the work.