At the end of the 19th century, a systematic restoration of the monument was undertaken, through which an ethic of monumental restoration was developed in one of the first cases of the application of archaeology and history to rebuild a structure in a historically accurate way. This was possible because of the combination of four factors: • The involvement of pioneering specialists in restoration including Johann Rudolf Rahn, one of the founders of the
Swiss Society of Historical Monuments in 1880, and , a specialist in
Renaissance architecture who was closely associated with the restoration of buildings such as the Romanesque in
Saint-Sulpice, the in
Lausanne, and the
Lausanne Cathedral. The initial lead architect of the restoration at Chillon was
Ernest Burnat, who had worked with de Geymüller in restoring Lausanne Cathedral. He initiated a general survey of the fortress, which was continued and intensified by his replacement as lead architect-archaeologist, , who played a major role in the development of archaeology in the Canton of Vaud. Naef devoted twenty years to the study of Chillon. Subordinating aesthetics to historical accuracy, he undertook detailed research into historical archives and conducted extensive archaeological excavations. The process was conscientiously documented in plans, sketches, photographs, and a journal kept by Naef. Until it was abandoned in 1908 the restoration followed a painstaking process of indicating replacement stones with inscriptions on the cut stone (R = Restored; RFS = Restoration facsimile; RL = Free Restoration), or by a change of colour or a red line on the masonry. From the outset, the Association aimed for an "artistic" restoration with the intention of "giving back to objects the character with which they were clothed, almost a latent life, a life impression of the ideas of their time". It is also planned to create a historical museum at the castle. • The appointment in 1889 of a Technical Commission comprising renowned art historians and architects who specialised in monument restoration. Alongside Rahn and de Geymüller, it included Théodore Fivel, architect in
Chambéry and connoisseur of Savoyard castle architecture, , restorer of the , and State architect
Henri Assinare. The Commission first met on 27 October 1890 and closely supervised the restoration over subsequent years. De Geymüller played a key role in its success. Drawing on principles published in 1865, and enhanced in 1888, by the
Royal Institute of British Architects, he established a framework in the
Milestones for the Restoration Program printed in
Lausanne in 1896. The result was judged to be exemplary. In an 1898 lecture to the
Zurich Antiquity Society,
Johann Rudolf Rahn boasted about it, while the German Emperor,
William II, inquired about the Chillon model when planning the reconstruction of the fortress of
Haut-Koenigsbourg. Due to these restorations, the castle is in excellent condition and is a good model of
feudal architecture. == Tourism ==