This question is inspired by this news article: Canada and Denmark reach deal to divide uninhabited Arctic island
I was thinking "why didn't they just alternate ownership of the island like what France and Spain do with Pheasant Island"? Pheasant Island was the site of the 1659 Treaty of the Pyrenees. The painting of the occasion, "Meeting on the Isle of Pheasants", appears to show that a rather ornate building was built on the island for the treaty to take place in.
How accurate this scene? I've looked at satellite photos of Pheasant Island, and the only structures I can find on the island are a monument to the Treaty of the Pyrenees and a retaining wall around the island, so what was actually built on the island for this treaty? It seems like quite a lot of engineering work to build this ornate building on such a small island, let alone back in 1659.
The painting by Laumosnier is absolutely accurate, and we know with a great deal o precision what was made for the grand occasion, and by whom.
Diego Velázquez (yes, that one) was the chief of protocol of king Felipe IV of Spain, and he was put in charge of creating a spectacular scenery for the signing of the treaty between the crowns of France and Spain, and he did a fine job at that.
The scenery was of paramount importance, but it would be something ephemerous in and of itself. After the treaty, it would be of no use, hence the need for something spectacular but not necessarily super expensive. Think of it as the carpentry for a theatrical play, something extremely complex and intricate, but also made of perishable materials. It's also something that should be assembled and dissasembled without much problems, even if we are getting something for the Grand Theatre of the World.
Velázquez was not foreign to the complexities of ephemerous yet gorgeous scenographies, as he was king Philip's chief of protocol, but also best buds with Pedro Calderón de la Barca, the great playwright who created many comedies that would be premiered in the royal palace. With this experience under his belt, Velázquez created a pavillion that would be made of wood, easily assembled, and that should be ready in nearly no time. This in itself is a display of the capabilities of the Spanish engineers, carpenters, and designers, which is a bit like the famous Field of the Cloth of Gold, but on a much more modest scale.
Protocol can be itself a branch of theatre, and Velázquez knew it. Symmetry became of paramount importance, with the French and Spanish delegations getting equal treatment, equal space, adequate deliberating rooms, etc.
Besides the painting there are a couple very interesting etchings, one showing the general blueprints of the pavillion, with precise measures, which I leave here.
https://gallica.bnf.fr/ark:/12148/btv1b550039095/f1.item.zoom
The other one, by Adam Perrelle, gives a general view, which completes the other one
http://bdh-rd.bne.es/viewer.vm?id=0000022051
And finally I will not pass the chance to offer Diego Velázquez's design, which for some reason is in the Military Archive of Stockholm.
http://www.4gatos.es/MemoriaAusente/idiomas/espanol/fichas/letraI/ifaisanes228.htm?lis=m2