There’s an interesting article in The Guardian about the growing number of paintings which no longer travel from their home repositories. The reasons are plenty, including fragility (Degas’ Danseuse), weight (The Winged Victory of Samothrace), size (Veronese’s Wedding Feast at Cana), or size AND fragility (Gericault’s The Raft of the Medusa). Another recurring hindrance to loans comes in the form of restrictions imposed by the donor or collector – the Barnes Collection restriction being one of the most well-known in the US. Oddly, value is not mentioned as a reason.
Vermeer’s Girl with a Pearl Earring, above, no longer travels from the Mauritshuis as, like the Mona Lisa, it has become such a visitor draw that the museum must keep it on permanent exhibition.