Yes, the Chehel Sotoun palace is not visible on this photo or from Ali Qapu in general. Chehel Sotoun is quite a low building and surrounding trees are quite tall. I don't remember if there are some higher viewing platform in the rear of Ali Qapu tower – I don't think so. But if there were, then it could be possible to see Chehel Sotoun itself.

This photo is taken with ultra wide angle lens (16 mm full frame) so the garden seems to be quite far away. My intention was not to take photo of garden but the alley and domes behind Ali Qapu. With some normal lens, let's say 35 mm or more, the view to the garden should be remarkably better.

Funny you should say that! I had drawn lines from the mid rear of Ali Qapu on Google Satellite View to replicate the furthest left and right of your photo to help me determine what was where and had noted how "wide" the angle was! As you say - great for your original purpose but not so good for showing up the Chetel Sotoun gardens. The nearest point of the Gardens to the wall of Ali Qapu from where you took the photo is around 270 metres and around 400 metres to the Chetel Sotoun itself - so, indeed, not that far away!

You can totally see the back wall of the Jongmyo Compound from the gate of the Changdeokgung Palace. The compound wall is part of the world heritage site, so you can definitely see it.

Can you??? The main entrance to Changdeokgung is a fair bit away from the Jongmyo Compound and there are modern buildings between the 2. Here is Google street view from the Changdeokgung entrance steps looking toward Jongmyo - the wall is hidden I believe at that point.
https://www.google.co.uk/maps/@37.5777897,126.9899264,3a,75y,116.72h,74.6t/data=!3m6! 1e1!3m4!1sdVzY_5wd-U1zZvOZJlxjAQ!2e0!7i13312!8i6656

The inside walking areas of both WHS are mapped on Street view and I have tried to find a view of one from the other by following the various paths.
My only "possibility" so far is this very poor view of trees which could be in Changdeokgung seen from inside Jongmyo - but I have a horrible feeling that the wall/gate is in fact an extra internal security wall behind the "old" one and the trees are not actually across Yulgok-ro
https://www.google.co.uk/maps/@37.5772242,126.9930689,2a,75y,18.84h,85.98t/data=!3m6! 1e1!3m4!1sMnHvJVpt_VUbtLDhb7q2Kg!2e0!7i13312!8i6656

This is the view from Yulgok-ro towards Jongmyo at the same place - NO Gate!!!
https://www.google.co.uk/maps/@37.5776098,126.9931306,3a,90y,211.44h,98.26t/data=!3m7 !1e1!3m5!1srK2fGaVGpnC8eSsLdbcGgg!2e0!6s%2F%2Fgeo0.ggpht.com%2Fcbk%3Fpanoid%3DrK2fGaV GpnC8eSsLdbcGgg%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26 w%3D203%26h%3D100%26yaw%3D219.61978%26pitch%3D0%26thumbfov%3D100!7i13312!8i6656

A possible conclusion is that, whilst one can see the walls of each WHS from e.g Yulgok-ro that can't count because one isn't actually "inside" either of them and are not therefore seeing one "from" the other!!
Help us out winterkjm!!!!!

From my experience, I would say that from the pathway bridge that once connected Jongmyo Shrine and Changgyeonggung Palace, you could see the wall of Changdeokgung Palace clearly, it was the stonewall on the left side of the bridge. But from the google street view, such bridge is not there anymore! I don't know that they will rebuild this bridge or not?

Thanks Durian - Which explains this structure in Yulgok-ro
https://www.google.co.uk/maps/@37.5776437,126.9930233,3a,90y,59.76h,83.34t/data=!3m6! 1e1!3m4!1sSmwMO1SUCBU2NSGfgv6gUw!2e0!7i13312!8i6656

Google maps shows more clearly the earlier existence of pathways on both side of the remains of this bridge (they have been removed in the more recent satellite view below) -
https://www.google.co.uk/maps/@37.5774456,126.9930238,19z

This turns out to have once connected the 2 sites at the location I suggested above for where one might be able to see the trees of Changdeokgung from Jongmyo. This satellite view shows it better and also confirms that the paths leading to the bridge have been removed and that there is an additional (temporary or permanent for security?) wall inside the old one at this point in both WHS- which means that views of "walls" from inside Changdeokgung on the other side are really only showing this modern inside wall) -
https://www.google.co.uk/maps/@37.5765085,126.9939013,127a,35y,339.62h,45t/data=!3m1! 1e3

From the above satellite view I would still conclude that the trees which can just be viewed on the other side of the new interior wall at this point ARE likely to be across the sreeet in Changdeokgung (Google maps puts the distance to the trees across the street at only around 40 metres) https://www.google.co.uk/maps/@37.5772242,126.9930689,2a,75y,18.84h,85.98t/data=!3m6! 1e1!3m4!1sMnHvJVpt_VUbtLDhb7q2Kg!2e0!7i13312!8i6656
Whether we want to count such a view as constituting "viewable" for the purpose of this Connection is another matter? Have we set a precedent with the Chetel Sotun "trees" from Ali Qapu?

The Eiffel Tower can be seen from Le Corbusier's atelier in Paris (Immeuble locatif à la Porte Molitor). Proof.

I have no more insight than already shared. All I know is that there is no worthwhile view from one site to another.

"Along with Changdeokgung and Changgyeonggung palaces, Jongmyo originally formed part of an exclusive zone in the heart of old Seoul. It now lies apart from the two palaces across a road, which the Japanese made to "cut off the vein of Joseon" during their colonial rule in the early 20th century." - Cultural Heritage Administration

The belltower in Brugge is part of the Belfries of Belgium and France site, and has a fine view of the Historic Centre of Brugge. I'm not sure, but there's a chance that you can see the Béguinage from the top too.

From the Le Corbusier house in Vevey, I believe you can see the Lavaux Vineyard Terraces.

In picture 12 in the link the Beguinage is visible from the Belfry (Bruges):
http://dsphotographic.com/photos/bruges/

Oh nice call. From what I can check, the inscribed area pretty much surrounds the Villa without being contiguous.
Importantly the hills behind are inscribed and they can clearly be seen from the Villa, even if I can't make out a distinct vineyard.

On the Brugge one we have ruled out any sites that join each other/ or the same building is inscribed multiple times as there are already connections for them. Though the view from the Belfry of the Beaguinage probably isn't covered by those. I think there may be a chance you can see the Belfort from the Beguinage as well, but I can't find any proof.

I've stayed with friends in the hills behind, surrounded by the vineyards, and can confirm that you can see the villa from there.

I was also wondering if you can see the Reims cathedral from any of the champagne caves. I imagine you'd be able to see the top of it from some of them.

Google Street view suggests not - the Cathedral is tucked away a bit and there is no straight view from the Northern edges of the inscribed "Cave" area to the South around 1.5kms away. Try it!

Cathedral may not work (though it is rather prominent from the ring road of Reims).

However the Basilica of St. Remi is part of the Cathedral inscription and that is much closer to the caves, about 250 m from Tattinger and not much more to Veuve Cliqout.

I certainly saw it whilst driving around the area, but I haven't yet found a view that shows a line of sight between two inscribed areas, perhaps from the towers of the Basilica or Upper Floors of one of the Champagne Houses?

Yes!!!!
If we take this map of the inscribed site - http://whc.unesco.org/document/107153
The Rue du Grand Cerf forms the ground level boundary of the site in the NW part of the Reims sector (I will ignore "underground" boundaries). The actual boundary would presumably be along the house fronts on the Eastern side which would make St Remi easy to see from inside any one of them (but not simply from the "trottoire" since it is probably not part of the inscribed area?). But never mind - go East a bit into e.g Rue Saint-Sixte. Certainly inside the UNESCO map "purple area" - and with a side view of St Remi -
https://www.google.co.uk/maps/@49.2437644,4.0443108,3a,60y,262.87h,89.12t/data=!3m6!1 e1!3m4!1sXgQZW8Vn1D6GH5atv3d0Zg!2e0!7i13312!8i6656
There may be "better" views from other locations.
So Former Abbey of St Remi element of Reims Cathedral can be seen from inside the "Champagne Hillsides, Houses and Cellars".
By the way - I don't think they are "contiguous". The UNESCO map shows a small part of the inscribed area of St Remi reaching the Rue du Grand Cerf but NOT crossing it or reaching its centre - so we must presume that this street will not be inscribed in either of the 2 sites