I made a map of destinations to go. I already live in DC, so I can just go the the national gallery of Art for free.
The red line is an outside Italy trip to London, Paris, Munich, Kracow, and St. Petersburg which all have art galleries featuring his work. The purple line is roughly where the Loire Valley is which I MIGHT visit on >>1524870
's behalf. Plus a purple line to Scotland where there is one painting on display, but it's a small cut of the pie and this trip is already looking pricey.
Once I get finish in St. Petersburg I'll fly to Venice (the green line being the Italian portion of the trip). From there Milan, Flounce, Rome, and Parma but I forgot to mark that. I haven't looked at rooming prices or anything, or even cost of food, flying from Russia to Venice, train fairs, or anything more than the initial flight from DC to London.