question: Why would old structures like Norte Dame or Sisten Chapel take awhile to restore. Don't we have 1000 times better Architecture Technology? What makes them hard to restore in the case of Notre Dame I hear it might take years.
comment: Restoration is painstaking work, because the goal isn't just to build something, it's to preserve as much of the original as possible, while filling in the missing parts. The first question is how much filling in do you want to do? The argument for minimal restoration (make the structure safe, prevent further loss) is that the artworks of the past should be preserved as best as possible, but nothing should be added that might detract from them. The argument for a full restoration (do whatever it takes to make it like new) is that you are bringing the structure back to the state its builders intended it to be seen in, and that trumps preservation of worn, damaged, or partially destroyed works. And of course there's arguments for every tiny step between those extremes. Then comes actually doing it, and hoo-boy. Do you know how many master stonecarvers, or stained glass makers, or fresco artists are still around? The answer is not many. An extensive restoration of a structure like a major cathedral might require re-learning of artistic disciplines that have been extinct or nearly extinct for centuries.
passages: Our works in stone, in paint, in print are spared, some of them for a few decades, or a millennium or two, but everything must finally fall in war or wear away into the ultimate and universal ash. The triumphs and the frauds, the treasures and the fakes. A fact of life. We’re going to die. "Be of good heart," cry the dead artists out of the living past. Our songs will all be silenced – but what of it? Go on singing. Maybe a man’s name doesn’t matter all that much.
   other options include rebuilding in the original lead and wood,
  
  rebuilding with modern materials not visible from the outside (like the reinforced concrete trusses at Reims Cathedral),
  
  or a combination of restored old elements and newly designed ones.
   These temporary measures will remain in place until more permanent solutions can be determined. Various studies are under way to determine with more assurance what can be done to preserve the structure. Columbia University is performing a study on a three-dimensional model constructed using laser scans of the building in an attempt to determine the weaknesses in the building and remedies.
  
  Section::::Interior.
   Most churches have been rebuilt, often several times, but medieval palaces and large houses have been lost at a far greater rate, which is also true of their fittings and decoration. In England, churches survive largely intact from every century since the 7th, and in considerable numbers for the later ones—the city of Norwich alone has 40 medieval churches—but of the dozens of royal palaces none survive from earlier than the 11th century, and only a handful of remnants from the rest of the period. The situation is similar in most of Europe, though the 14th century Palais des Papes in Avignon survives largely intact. Many of the longest running scholarly disputes over the date and origin of individual works relate to secular pieces, because they are so much rarer - the Anglo-Saxon Fuller Brooch was refused by the British Museum as an implausible fake, and small free-standing secular bronze sculptures are so rare that the date, origin and even authenticity of both of the two best examples has been argued over for decades.
   Section::::Architecture.:Restoration.
   BULLET::::- The 1978 Palace of Versailles bombing severely damaged parts of the Palace of Versailles, including several priceless pieces of art. The palace was rebuilt and reopened to the public within four years.
  
  BULLET::::- On 15 April 2019, the roof of the Notre-Dame de Paris caught fire, severely damaging the bell towers and resulting in the total collapse of the central spire and roof. The fire is believed to be caused by the ongoing restoration, though an investigation is ongoing.
  
  Section::::Germany.
   In December 2016, 170 years after the North Towers dismantlement and following several false starts, the Ministry of Culture again proposed its reconstruction after concluding it was technically feasible—albeit without public funding. An association, "Suivez la flèche" ("Follow the Spire"), chaired by Patrick Braouezec, has since been established to support the reconstruction, with the aim of raising the necessary funds by opening the reconstruction works to the general public, along the model of the Guédelon Castle. In March 2018 the culture ministry signed an accord with the association, officially launching the reconstruction project, with works expected to commence in May 2020. 
   These changes in church architecture and design have been criticized from an artistic standpoint. Many historic and irreplaceable works of art have been discarded or destroyed during these renovations. The end results of many renovations have also been criticized as unattractive and not an improvement from the pre-concilliar designs.
   While Macron hoped the cathedral could be restored in time for the 2024 Olympic Games in Paris, architects expect the work could take from twenty to forty years, as any new structure would need to balance restoring the look of the original building, using wood and stone sourced from the same regions used in the original construction, with the structural reinforcement required for preventing a similar disaster in the future.
  
  There is discussion of whether to reconstruct the cathedral in modified form.
  
  Rebuilding the roof with titanium sheets and steel trusses has been suggested;
   Section::::Controversy over the cleaning and restoration.
   The 2019 fire left the three great medieval rose windows essentially intact, but with some damage. The rector of the Cathedral noted that one rose window would have to be dismantled, as it was unstable and at risk. Most of the other damaged windows were of much less historical value.
  
  Section::::Crypt.
   The third factor affecting ancient building conservation is tourism. While tourism provides both economical and cultural benefits, it can also be destructive. The Egyptian tomb of Seti the 1st is currently off limits to the public due to the deterioration that has been caused by tourists. The pyramids in Giza have also encountered problems due to large numbers of tourists; more tourists mean greater humidity and water presence, which can lead to erosion.
  
  All of the above factors complicate the conservation options available to treat these buildings.
  
  Section::::Conservation process.
  
  Section::::Conservation process.:Assessment.
   Section::::Sights.
  
  Three medieval buildings remain on the Île de la Cité (east to west):
  
  BULLET::::- Cathedral of Notre Dame de Paris, built from 1163 on the site of a church dedicated to Saint Étienne, which in turn occupied a sacred pagan site of Roman times. During the French Revolution the cathedral was badly damaged, then restored by Viollet-le-Duc. The Cathedral was heavily damaged, but not totally destroyed, in a fire on 15 April 2019, while undergoing the initial stages of a massive renovation- materials from the renovation are currently believed to have started the devastating, large fire.
   Although estimates vary (depending on how one counts compound or grouped windows) approximately 152 of the original 176 stained glass windows survive – far more than any other medieval cathedral anywhere in the world.
   While undergoing renovation and restoration, the roof of Notre-Dame caught fire on the evening of 15 April 2019. Burning for around 15 hours, the cathedral sustained serious damage, including the destruction of the flèche (the timber spire over the crossing) and most of the lead-covered wooden roof above the stone vaulted ceiling.
  
  Section::::History.
   Some contents were moved by a human chain of emergency workers and civil servants.
  
  Many valuables that were not removed also survived, but the state of many others remained unknown as of 16 April.
  
  Lead joints in some of the 19th-century stained-glass windows melted, but the three major rose windows, dating to the 13th century, were undamaged. One weakened window may need to be dismantled for safekeeping.
  
  Several pews were destroyed and the vaulted arches were blackened by smoke, though the church's main cross and altar survived, along with the statues surrounding it.
   BULLET::::- Le Mans Cathedral A church dating to 1160 on the site burned, together with much of Le Mans, on 3 September 1134, with a second fire in 1137. The chevet survived, and a new nave was constructed. The chevet was eventually rebuilt between 1217 and 1254.
  
  BULLET::::- Metz Cathedral Fireworks caused a fire in 1877.
  
  BULLET::::- Nantes Cathedral A fire on 28 January 1972 extensively damaged the roof, requiring a full restoration of the cathedral's interior.
  
  BULLET::::- Noyon Cathedral was built following a fire in 1131.
   BULLET::::- Beauvais Cathedral Three fires led to the start of a replacement for the former basilica at the site. The Basse Oeuvre is the remnant of the original church, having survived fires in the 11th and 12th centuries. The ambitious project suffered from structural instability, leading to repeated collapses, in 1284 and 1573.
  
  BULLET::::- Belfort Cathedral A timber church on the site was destroyed by fire in 1212.
   The valid contributions of all periods to the building of a monument must be respected, since unity of style is not the aim of a restoration. When a building includes the superimposed work of different periods, the revealing of the underlying state can only be justified in exceptional circumstances and when what is removed is of little interest and the material which is brought to light is of great historical, archaeological or aesthetic value, and its state of preservation good enough to justify the action. Evaluation of the importance of the elements involved and the decision as to what may be destroyed cannot rest solely on the individual in charge of the work.
   On the week of 16 November 2015, restoration work on the cathedral concluded.
  
  Section::::Current Use.
   Much of the chapel as it appears today is a re-creation, although nearly two-thirds of the windows are authentic. The chapel suffered its most grievous destruction in the late eighteenth century during the French Revolution, when the steeple and baldachin were removed, the relics dispersed (although some survive as the "relics of Sainte-Chapelle" in the treasury of Notre Dame de Paris), and various reliquaries, including the "grande châsse", were melted down.
  
  Section::::Later reception and restoration.:19th-century restorations.
   In 1836, due to the negligence of workmen, a fire began which destroyed the lead-covered wooden roof and the two belfries, but the building structure and the stained glass were untouched. The old roof was replaced by a copper-covered roof on an iron frame. At the time, the framework over the crossing had the largest span of any iron-framed construction in Europe.
  
  Section::::History.:World War II.
   BULLET::::- Reims Cathedral An earlier Our Lady of Reims was destroyed by fire on 6 May 1210. Work on the present building began a year later.A fire in 1481 destroyed the attic framing, central tower and aisle gallery roofs. During World War I, German shelling set fire to scaffolding at the north tower, destroying the roof and the bishop's palace. In both cases, the lead roofing material melted. After the war, the cathedral roof was reconstructed using concrete framing.
   Section::::Conservation process.:Treatment.:Case example: Ancient stone structures.
  
  Most ancient buildings are constructed of stone and have survived from antiquity as a result of the stability of this building material. However, stone can deteriorate rapidly without protection, particularly in our modern era of pollution and climate change.
  
  Section::::Public awareness and outreach to promote architectural conservation.
   On 15 April 2019, just before 18:20 CEST, a structure fire broke out beneath the roof of Notre-Dame de Paris cathedral in Paris. By the time it was extinguished, the building's spire and most of its roof had been destroyed and its upper walls severely damaged; extensive damage to the interior was prevented by its stone vaulted ceiling, which largely contained the burning roof as it collapsed. Many works of art and religious relics were moved to safety early in the emergency, but others suffered some smoke damage, and some exterior art was damaged or destroyed. The cathedral's two pipe organs, and its three 13th-century rose windows, suffered little to no damage. Three emergency workers were injured.
  