The sites connected to "Protective Shelters" are relatively difficult to double check, as (a) you would have to have visited it to remember if it has a shelter, and (b) shelters are often temporary. So can anyone tell more about those below?

- Ban Chiang >> how is this covered? is it a museum?
- Temple of Apollo Epicurius at Bassae >> this one has been covered by a plastic tent for at least a couple of years. Is it still covered now?

Having not visited I am not sure if it was just a short term protective cover, but the bas relief on the stair case at Persepolis seems to be covered by some sort of protective cover whenever I have seen it on documentaries.
Does anyone have any knowledge of it? The two documentraies I am thinking of would have been filmed in about 2003-2006 so it may have just been a temporary fixture.

For Ban Chiang, the archeological site is protected by a very nice shelter made by corrugated iron roof similar with the infamously one of Gal Vihara so it's quite permanent. For artifects are kept in the museum buildings.

The "temporary protection" at Bassae has been there a lot longer than "a couple of years" - since 1987 in fact. The 2004 ICOMOS "State of Conservation Review" did not expect its removal in the foreseeable future :-
".. installing a temporary protection cover on the monument (1987)...... Over the past 17 years it has been proved that the shelter protects the temple's fragile material from the direct effects of weather phenomena and it has contributed decisively in halting the deterioration of the stones. Despite the fact that the form of the shelter expresses its temporary nature, and it differs from the architectural shape of the monument, the scientific committee is exhaustively investigating the matter in order to find a permanent solution for the protection of the temple"

This link
http://www.fordham.edu/gsas/phil/babich/Babich-From%20Van%20Goghs%20Museum%20to%20the %20Temple%20at%20Bassae.pdf
has a rather intellectual, but possibly interesting, philosophical discussion from 2003 on the concept of "preservation" by separating historical objects from their context by "taking Heidegger's discussion of the strife between earth and world to the site of the ancient temple of Apollo Epicurius at Bassae as an example of the insistent foreclosure of the ancient work of art and the conflicts of the pervasive efforts of modern conservation". If that proves too cerebral it also contains photos of said "temporary protection" which it describes as "a weirdly circus-like structure of ungainly proportions, the covering tent builds the closed space of modern vanity – a permanent temporary scaffolding – around the temple: a mindless gesture of affected protection from the elements, secluding and so refusing them as the elements which the temple was first set up to articulate" !!!!