They should just trap Julian Baumgartner inside for a month, with nothing but water, food, and conservation-grade varnish and reversible pigments, and the whole place would look like new!
one should bear in mind, that Constantinople at that time was still Christian and most of the goods, that were ransacked, came to Venetia
Time for a new crusade anyway. Let's cleam up this mess from Al-Londonista via Al-Andalusia all the way to Constantinoble.
The actual picture without zoom disabled.[1] In case you wanted to look at it.
[1] https://api-www.louvre.fr/sites/default/files/styles/w1059_h...