I have just bee reading a few of the other posts and it seems that this is an issue that has turned up a fair few times in our discussions so maybe we should put it forward for full debate.

What are forum members opinions on World Heritage sites made up of a series of sites?
Does this indicate that one site by itself is not good enough to get on, so attaching a lot of other sites adds to its chances of getting on the list?
-or-
Does including serial sites make it better as the full context of the inscription can be appreciated.

Should the World Heritage List mostly be the reserve of select exceptional monuments?

To put in my own views; I do think there is quite a strong case for serial nominations.
To highlight this I present a few examples where this method works well;
Sites associated with one particular person (e.g. an architect) where there works are better displayed as a group, instead of picking one particular building. The potential upcoming inscription of the works of le Corbusier is a great example of this. The sites chosen reflect his work across continents and decades ad give a great understanding of what makes the sites important.
In counter balance the Tugendhat Vila in Brno is the only inscribed site designed by Mies Van der Rohe. His works post-war works in the USA illustrate many of the developments he pioneered. Whilst I feel the Seagram Building in New York is of a standard worthy of inscription on the list, I could not imagine Mies' works being inscribed as two separate WHS.
N.B. this is not saying that every inscribed architect should have their whole canon of works inscribed; The inscription of the Sydney Opera House would if anything be lessened if Utzon's other works were inscribed as part of the same site.

Also particular types of buildings can work well together. The inscription of multiple Maltese Temples works well. The original inscription of just one set of temples is complemented by the extension to include several examples.

I think that one particularly good example of how the serial nomination has worked is the Frontiers of the Roman Empire site. Being a little naïve I had no idea that the empire constructed limits all across Europe, this inclusion of sites in German was great in highlighting this to me. I think that the German lines and the Antonine wall would not be of sufficient value to be inscribed by themselves, however in addition to Hadrian's Wall they really add to the context.

Now this will never happen; however I was thinking about the merits of turning already inscribed sites into serial sites. After Khuft mentioned them on a previous post, I was thinking about the 'folk villages' of Vlkolinec, Hollokö and Holasavice. They are currently inscribed as three separate sites, I have only visited Holasavice but did not find it particularly remarkable. I think there is a good reason for these sites to be on the list however would including them as some kind of over arching 'Folk villages of Central Europe' type inscription be worth considering?
I appreciate that causes a lot of potential problems, what can and can't be lumped together, where to stop with the links. However could sites such as: Gothic Cathedrals of North West Europe, Italian Renaissance Towns, Palaces of the 17th Century, Planned Colonial towns of early Latin America help to tidy up some of the denser parts of the list?

I'm a fan of serial sites too - for some concepts there may be more than one / many relevant sites without one by itself warranting inscription.
Struve Geodetic Arc is a case in point (whatever you think about the relevance of the listing itself): none of the individual sites would have made sense individually. The Fortifications of Vauban, on the other hand, show Vauban's talent in different geographical settings - thus highlighting the genius of Vauban in adapting the fortresses to the the respective terrain.

Also, serial sites help allow an increase of the number of listed monuments without an actual increase of listed sites.

Finally: in some cases various monuments may be of equal importance, but listing more than one would bloat the list. The Belfries of France and Belgium highlight both the benefits as well as the danger of this approach: among the +50 listed belfries, it would be difficult to choose the 1 most relevant belfry, but listing +50 is certainly self-defeating... we might as well list all gothic churches in Europe.

here is the official document related to serial sites from the world heritage website:
http://whc.unesco.org/download.cfm?id_document=9957

note that in the document, there is an explicit statement on the limit of the number of elements for one specific whs (i.e. belfries of belgium and france).

Personally I'm a fan of serial sites. At least, where monuments are concerned. i don't think that most individual buildings are significant enough to be inscribed on their own, but when together they make a whole that is greater then the sum of their parts.
Cities, on the other hand, I believe do not adapt so easily to being inscribed in a serial manner. Each city has its own character, its own identity, so inscribing them in unison emphasizes only the similarities and fails to highlight the differences. so unless cities are very very similar, i oppose serial nomination,
The Struve Geodetic Arc is, of course, the ultimate example of where inscribing in serial is absolutely necessary. By themselves, they would have no meaning as a world heritage site. By themselves, they would have no more significance then inscribing, say, the battlefield of Quadesh (site of the world's first peace treaty, but there is nothing there). together, the sites become much more significant.

does anyone have a complete list of world heritage site that are serial in nature? just would like to see the yearly trend. of course, the inventory for old sites is also likely to change based on the retrospective inventory. given that before, documentations and data are lacking, only to find out based on recent clarifications that the sites are actually serial sites.

I don't have totally clear understanding of how we are defining Serial sites, partly because, as m_m points out, the documentation of many earlier sites is incomplete and possibly incorrect and there has been no standardisation of use of terms over the life of the scheme. Indeed, in a quick review of sites I had always considered were "serial", I haven't found the term used in official UNESCO documentation.

The UK "Cornwall and W Devon Mining Landscape" is described in the Advisory body evaluation as "In terms of the categories of cultural property set out in Article 1 of the 1972 World Heritage Convention, this is a site (My emphasis!!). In terms of the Operational Guidelines for the Implementation of the World Heritage Convention (2 February 2005) paragraph 47, it is also a cultural landscape. "
Yet it has 10 different locations inscribed - all of which except 1 have the phrase "mining district" in their title (the other is a "Port" and 1 of the mining districts also includes a "town"). In my view a clear "serial site"? UK could have chosen just the best of mining districts - because it didn't it has created a serial site - correct?

If I look at "Rock art of the Mediterranean basin" the advisory body evaluation states that "In terms of the categories of cultural property set out in Article 1 of the 1972 World Heritage Convention, this nomination consists of a group of sites." This site has 727 different locations -all of which contain rock art of one sort or another. Is a "group of sites" the same as a "serial site"? If any site is a "serial site" then surely this must be?

For the "Flemish Beguinages" the advisory body states "In terms of the categories of cultural property set out in Article 1 of the 1972 World Heritage Convention, Flemish Beguine convents are groups of buildings." This "site" has Beguinages in 13 different locations
Is there a difference between a "multi location site" and a "serial site"? if so I would be interested to hear a definition of the distinction!

Are these "serial sites" or not? No official document seems to call them such. So, is any "multi location site" by definition a "serial site" or do the different locations have to be "similar" in nature to be "serial"? For instance, St Petersburg consists of 81 different locations, but many of these are different "types" of location. But it does contain numbers of the same type of sites e.g multiple forts and palaces. It could have chosen just the best of each but has chosen to choose a "series" - surely again that makes it a serial site"? But what about a multi location site which consists of just a single example of each of a number of different types of sites e.g a "Fort", a "Palace" and a "Railway" - is that a "serial site".

In the case of Natural sites the argument might be that each of the locations is subtly different from, rather than just a duplicate of the others -but this seems no different from stating that, in a site of multiple belfries, each belfry is subtly different.

If we can agree that Serial site = Multi location site then it would be simple to hold the number of "locations" ("sub-sites" or whatever else they are called) on this web site as an extra piece of data whcih should come in useful! I am happy to take a sub set of countries and identfiy the numbers of location numbers for each of their sites

The Operational Guidelines have the following info about serial nominations. Not very clear in my opinion:

Serial properties
137. Serial properties will include component parts related because
they belong to:
a) the same historico – cultural group;
b) the same type of property which is characteristic of the
geographical zone;
c) the same geological, geomorphological formation, the
same biogeographic province, or the same ecosystem
type;
and provided it is the series as a whole – and not necessarily the
individual parts of it – which are of outstanding universal value.

138. A serial nominated property may occur :
a) on the territory of a single State Party (serial national
property); or
b) within the territory of different States Parties, which
need not be contiguous and is nominated with the
consent of all States Parties concerned (serial
transnational property)

139. Serial nominations, whether from one State Party or multiple
States, may be submitted for evaluation over several
nomination cycles, provided that the first property nominated
is of outstanding universal value in its own right. States
Parties planning serial nominations phased over several
nomination cycles are encouraged to inform the Committee of
their intention in order to ensure better planning.

The Housing Estates in Berlin (2008) clearly is a serial site, and this is also made clear in the nomination file: serial nomination of six groups of buildings.

Of the ones named above, I would guess that at least the beguinages and the rock art are serial sites too. A cultural landscape (like Cornwall) will often/always have multiple locations, but can it be a cultural landscape AND a serial nomination at the same time??

despite the fact that there has been an increasing trend to using serial sites in recent years (and even as a way to get around the one cultural nomination per country per year limit), the definition of what a serial site is is still quite ambiguous. there are lots of different scenarios which need to be considered. for example, if a world heritage site is composed of different groups of sites in its core zone, but the buffer zone is just one entire space that captures all these elements in the core zone, is it considered a serial site?

hey, i found this publication from iucn with respect to serial natural and mixed sites: http://cmsdata.iucn.org/downloads/world_heritageserialsites.pdf

From IUCN evaluation on Dolomites, there are questions that need to be answered in order to be justified as serial site nomination; (section 5.1)
1. What is the justification for the serial approach?
2. Are the separate component parts of the nominated property functionally linked in relation to the requirements of the Operational Guidelines?
3. Is there an overall management framework for all the component parts of the nominated property?

So the state party need to have understandably reasons for serial site nomination? or not! as for Dolomites case, Italy has no overall management plan yet but IUCN still accepts the serial site concept with positive evaluation result by lacking overall mangement plan!!

http://www.ufficiostampa.provincia.tn.it/binary/pat_ufficio_stampa/notizie/dolomiti.1 242153447.pdf