I can find 4 to initiate the connection but have some questions about other possibles - any help?

Inscribed buildings (which can be visited) in which historically significant congresses, conferences or conventions were held. Sites of Legislative "parliaments" are excluded (see their specific Connection)

Potsdam - Schloss Cecilienhof -"Potsdam Conference" (1945) - Stalin, Churchill/Atlee and Truman to discuss the post WWII order
Cuidad Panama - Salon Bolivar - "Panama Congress" (1826) - organised by Bolivar in an attempt to promote pan-American unity
Independence Hall - "2nd Continental Congress" (1775-83). To manage the war effort (War of Independence)
Paris Banks of the Seine - The Paris Peace Conference (1919) to end WWI (The various treaties - Versailles, Saint-Germain, Trianon etc were signed elsewhere as per their titles) was held in the Salon de l'Horloge at the French Foreign Ministry in the Quai d'Orsay. See
http://www.diplomatie.gouv.fr/mae/visite_orsay/ind_orsay.html (It is a suggested "Connection" requirement that the location is capable of being visited! It was open to the public on European Heritage Day Sep 20 2008 and may well be on other such "special days"! http://www.mouvement-europeen.eu/Journees-europeennes-du-patrimoine-2008 )

There is slight possibility that the following also took place within an inscribed site. Does anyone know??
Congress of Vienna (1815) - to end the Napoleonic wars. But it doesn't look as if there was any single building since Wiki says "An unusual feature of the "Congress of Vienna" was that it was not properly a Congress: it never met in plenary session, and most of the discussions occurred in informal, face-to-face, sessions among the Great Powers with limited participation by delegates from the lesser states".
Congress of Verona (1822) - to discuss, inter alia, the intended invasion of Spain by France on behalf of Ferdiand VII. Since the historic centre of Verona is inscribed there might be a reasonable chance - unless some palace on the outskirts was used?
Congress of Paris (1856) - to end the Crimean War. I can find nothing which indicates its location - it might have been the Salon de l'Horloge again?

congress of Vienna definitely took place within the inscribed area.
Does this count any treaties whatsoever? or just large groups of people coming together to discuss things. For example, do university conferences count?

As always the proposed definition states "Historically Significant" in order to miss out the annual get-together of the Ancient Order of Buffaloes in wherever! The phrase possesses some flexibility - we could tighten it now or see where it takes us. I did think of "International" as a limitating factor - but didn't want to exclude any significant non-parliamentary meetings. What for instance was the status ("Internationally") of the 13 colonies when the 2nd Congress started - they were not yet a single state - but later they were and it wouldn't the have counted as "International". "Political" or "Diplomatic" were other possible limiters - but what do they really add?

I had thought of having a connection for "Treaties" per se as there certainly are a fair number whose title connects, at face value, to a WHS. Stralsund, Granada, Westminster (several), Paris (numerous), Edinburgh, Greenwich, Chambord, Blois, Lyons, Lubeck, Regensburg etc etc etc. But how to link them incontrovertably to the site? It would be necessary to know where in those places they were signed - after all, the potential interest in such "connections" (if there be any!) is about linking "location" and "historical events" so that one could stand somewhere (or look at a map or guide book or nomination dossier) and say "here occurred...."! I guess in the case of e.g Chambord it is unlikely to be anywhere other than the chateau but, to give the connection "meaning" it really seems necessary to know exactly where the treaty was signed and that is often remarkably difficult from available sources. It was less of a problem for at least some of the congresses/conferences.

If we do have a "connection" for this "type" of historical event we could either extend it to include treaties (if we know where they were signed) or have a separate connection for such treaties - many treaties, especially earlier ones involving royalty, did not come about as a result of formal "conferences" which provides some argument in favour of a distinction. Also, as with WWI, treaties don't necessarily get signed where the conference took place and of course not all congresses/conferences result in a formal "treaty" etc etc. If we did have both we would need to watch out for "double-counting" where a congress and treaty signing took place at the same location But we have similar problems with other "Connections" - e.g. rock cut buildings and rock cut art in locations which are also rock cut buildings. Since rock cut art also occurs in locations which are not buildings we need 2 "connections"! We just have to determine which is the more significant, give it primacy and stick to it. But I am still inclined for the moment to suggest keeping the 2 aspects separate - what do others think?
P.S. I still think we would need more evidence of "location" before the Congress of Vienna could be included.

how about the site of the warsaw confederation?

This wasn't a historical event of which I was aware!! Having looked it up (!!)
http://en.wikipedia.org/wiki/Warsaw_Confederation
it seems to support my view for not limiting the definition of "congresses and conferences" too tightly - there are just too many different types and circumstances. IF we knew exactly where in Warsaw it took place AND that place were within the inscribed area AND identifiable as an existing or ruined structure OR as a "legendary location" it would seem to me to justify being added to my proposed Connection (whose definition should therefore be framed to allow it).

One possible illogicality in my definition would seem to be the exclusion of "Legislative Parliaments" for which there is already a "Connection". Should not all political/diplomatic "meeting places", whether regular or one-off be in the same "Connection"? There is already a logical (but not a practical one for us since Washington isn't inscribed!) "problem" in that, for historical reasons going back to the Continental Congresses and the view of the colonies of their own sovereign nature, USA calls its "Parliament" a "Congress" when, in wider parlance, that word is used more strictly to involve representatives from different "countries". I personally am comfortable that it is worthwhile keeping a separate connection for "Parliaments" and that a single further connection for other political/diplomatic meetings should encompass all the others - for the moment.If we see a need for a subdivision (unlikely?) then so be it

We could spend a lot of time trying to find a more generic title than "Congresses and Conferences" for this proposed connection to include the wide variety of significant non-parliamentary "meetings" which have taken place over history! Better to cover such matters in the definition?

Just to add one to the list, The Tugendhat Villa was the location of the signing of the Velvet Divorce between the Czech and Slovak republics.

Just as we already identified a connection for locations of "Parliaments" as a special sort of "congress/conference/meeting" etc we have identified a connection for locations of "Declarations of Independence" as a special type of agreement/treaty/"document" - albeit a unilateral one as is the nature of "declarations"!!.
The issue now is do/should we have connections for other sorts of meetings/"documents"?

On reflection, the Velvet Divorce was perhaps more akin to a Treaty than to a "Declaration of Independence" anyway - as I understand it the actual "Declaration of the Independence of the Slovak nation" had taken place in the Slovak Parliament 6 days before the agreement at the Tugendhat villa

The treatises of Rome establishing the European Community which later became the EU were signed in 1957 at the Palazzo dei Conservatori on the Capitoline Hill. The preceding conferences were held in other places though.

Thanks Assif!
So we now definitely have enough sites for 2 new Connections.

Sites where treaties were signed See Wiki for definition of a "Treaty". Location/building of signing must be known and within the WHS. Declarations of Independence do not fit the definition (see separate Connection). Where a Treaty/Agreement was signed at the same location as a connected "Congress/Conference" it is "connected" with the more "famous" title
Rome - Treaty of Rome 25 March 1957. In Palazzo dei Conservatori
Loire Valley - Treaty of Chambord 1552. in Chateau de Chambord
Versailles - Treaty of Versailles 28 June 1919 . In Hall of Mirrors.

There will be others! I am inclined to leave the Tugendhat Villa under "Declarations of Independence" even if the actual "Slovak" declaration took place earlier in its Parliament.

Sites of Congresses, Conferences or Conventions. The meeting must have been historically significant. The buildings/location must be known and within the WHS. Legislative Parliaments are excluded (see separate Connection). Where a Congress/Conference led to the signing of a Treaty at the same location it is "connected" with the more "famous" title

Potsdam - Schloss Cecilienhof -"Potsdam Conference" (1945) - Stalin, Churchill/Atlee and Truman to discuss the post WWII order. Led to the Potsdam Agreement and Potsdam Declaration
Cuidad Panama - Salon Bolivar - "Panama Congress" (1826) - organised by Bolivar in an attempt to promote pan-American unity
Independence Hall - "2nd Continental Congress" (1775-83). To manage the war effort (War of Independence)
Paris Banks of the Seine - The Paris Peace Conference (1919) to end WWI (The various treaties - Versailles, Saint-Germain, Trianon etc were signed elsewhere as per their titles) was held in the Salon de l'Horloge at the French Foreign Ministry in the Quai d'Orsay. See http://www.diplomatie.gouv.fr/mae/visite_orsay/ind_orsay.html

do we also include here religious conferences, like ecumenical councils and elections of popes?

Possibly a little off the topic of congresses and conferences, but this was signed in what is now a World Heritage Site, and certainly is significant in UK history...

http://www.covenanter.org.uk/Greyfriars/

There have been a number of historically significant documents signed/"promulgated" etc at known locations within the boundaries of WHS which our current 2 document related Connections of "Treaties" and "Declarations of Independence" don't really encompass.
The National Covenant suggested by Nem is certainly one and I came across the "Revocation of the Edict of Nantes" which I hadn't previously realised is also known as the "Edict of Fontainbleau". A document which is significant within the history of a single nation justifies a "connection" I believe even if it isn't of "universal" significance? Or are we grinding too small?

Part of the problem goes back to the fact that we don't yet have clarity on a number of Connections in this area - for instance Independence Hall appears in
"Revolutionary Events", "Historical Events", "Congresses and Conferences" and "Declarations of Independence". I would suggest that this is 2 too many! The Declaration of Independence and the Continental Congress would seem to cover the Historical significance of the building as far as "events" are concerned - though perhaps a it should also be connected to Parliaments as it was earlier the location of the Pennsylvania State Legislature - our definition of "Parliaments" isn't limited to current ones and is perhaps too "vague" just using the word "Parliament" - something more generic like "Legislature" might be better to cover the range of possibilities where the word "Parliament" isn't used?

If we took Independence Hall out of "Revolutionary Events" however then we are only left with 2 (Storming of Winter Palace and Landing of the Granma!!). Perhaps Place de la Bastille should be added for its own "storming" event! Or else lose them within Historical Events?

If we do keep both sorts of "events" then, using the general rule we have adopted elsewhere that "the more detailed Connection trumps the less", a "Revolutionary event" would trump a mere "Historical event" so there is no need to put Independence Hall in the latter as well.

Back on Historical Documents I would suggest that we continue to have the 2 "detailed" ones we already have ("Declararations of Independence" and "Treaties") and introduce a third generic one "Historic documents" for any other we identify (We have the Covenant and Edict of Fontainbleau already and I might be inclined to move the "The Belavezha Accords" from Treaties as it wasn't really signed as a Treaty between existing sovereign states nor was it a true "Declaration of Independence"?) with a definition which makes it clear that Declarations of Independence and Treaties have their own specific "Connections"!