Right I hope no one objects but I have tried to break down the massive Religious Structure: Christian category (107!) into some slightly more manageable chunks.
I don't necessarily want people to pile in on it as the focus was on natural sites, I just had a bit of time to do it so dove in.

This batch (22) is those where the main focus is a Cathedral.

Aachen Cathedral
Amiens Cathedral
Assisi
Bourges Cathedral
Burgos Cathedral
Canterbury
Cathedral of St. James in Sibenik
Chartres Cathedral
Cologne Cathedral
Durham Castle and Cathedral
Echmiatsin and Zvartnots
Hildesheim Cathedral and Church
Kiev
León Cathedral
Modena
Notre-Dame Cathedral in Tournai
Piazza del Duomo (Pisa)
Reims
Roskilde Cathedral
Speyer Cathedral
Vatican City
Westminster

My selection:

Aachen
Amiens Cathedral
Assisi
Chartres Cathedral
Cologne Cathedral
Durham Castle and Cathedral
Echmiatsin and Zvartnots
Kiev
Piazza del Duomo (Pisa)
Saint Catherine Area
Speyer Cathedral
Vatican City

Ah you beat me to my edit I moved Saint Catherine Area over to residential as it is a monastery rather than cathedral

3 from UK seems "generous"! ???

My selection:
Aachen cathedral (perhaps the most important cathedral in Germany)
Assisi (mainly for its wonderful frescoes as well as its importance)
Hildesheim (one of the best examples of painted wooden ceilings worldwide)
Piazza del Duomo (one of the best ensembles of a duomo, baptistery and tower in a harmonious iconic setting)
Reims (one of the most representative cathedrals worldwide especially for its sculptures)
Vatican City (the most important site for Christianity and the Musei Vaticani alone are already of outstanding value)
Westminster (one of the most iconic in Europe and the UK)

Amiens Cathedral
Assisi
Chartres Cathedral
Burgos Cathedral
Cologne Cathedral
Piazza del Duomo (Pisa)
Vatican City
Speyer Cathedral

One thing that stood out is that there are a lot of European Gothic cathedrals. I think we could do with limiting the examples. Pisa seems obvious as inclusion anyway and has significant Gothic aspects, and then a sole northern European example, as others will be included in European cities anyway (e.g. Paris), also other inclusion have Gothic elements (e.g. Aachen)

Aachen Cathedral – Y – Perhaps the most important site for understanding the role of religion in European politics and culture. Also impressive architectural importance and longevity.

Amiens Cathedral –Y/N Either this or Chartres as the sole example of N. European Gothic, I prefer Amiens, but will readily concede Chartres is regarded as the most important.

Assisi – Y – Perhaps the best site to illustrate the veneration of saints, also impressive frescos.

Bourges Cathedral – N Think Chartres or Amiens are better examples

Burgos Cathedral –N- Better examples of gothic elsewhere

Canterbury – N?- Open to persuasion as protestant sites will be limited, but there are better examples of gothic cathedrals.

Cathedral of St. James in Sibenik – N- Regional significance only

Chartres Cathedral – Y/N – Either this or Amiens, Chartres is probably the most important

Cologne Cathedral – N?- if a second north European gothic cathedral is needed I would put forward Cologne as it is perhaps the most complete Gothic edifice, and took so long to build that it is actually a different version of the style.

Durham Castle and Cathedral – Y/N- Either this or Speyer as an example of Romanesque cathedral, my preference is for Durham due to the setting and column decorations.

Echmiatsin and Zvartnots – Y- Oldest cathedral in the world, in the first country to formally adopt Christianity as national religion (also bonus for not being in Western Europe!)

Hildesheim Cathedral and Church - N - I think Speyer or Durham would be better Romanesque examples, perhaps this is based on being locked out of it on a very cold December night though.

Kiev –Y- perhaps the finest Orthodox cathedral, large historical significance

León Cathedral –Y?- Need to include non European examples, but would places like Mexico City cover this anyway?

Modena – N- not interesting enough

Notre-Dame Cathedral in Tournai –N – better examples elsewhere

Piazza del Duomo (Pisa) –Y- finest Romanesque and gothic architectural ensemble anywhere.

Reims – N?- I would give preference to Chartres or Amiens, open to persuasion that this one is better though no more than one of the three.

Roskilde Cathedral – N? – Not an especially interesting building, but does represent Protestantism

Speyer Cathedral –Y/N- Either this or Durham for Romanesque, Durham gets my vote.

Vatican City –Y- Think this one is a dead cert, various pinnacles of European art in a small area, massive religious significance

Westminster – N- The Houses of Parliament are of more relevance, and would get my nod on that, also technically not a cathedral but hey ho!

Well argued - I have visited all but 2 and wouldn't disagree with any of the conclusions - though wouldn't claim to have the same detailed critical knowledge..
Agree that Latin America is probably better represented via Cathedrals included in cities/towns likely to be included. in my understanding and experience Leon Cath isn't strong enough on its own.
A point worth bearing in mind for all "individual building" WHS during this exercise I think!!

My selection:
Aachen Cathedral
Assisi
Chartres Cathedral
Cologne Cathedral
Durham Castle and Cathedral
Echmiatsin and Zvartnots
Kiev
Piazza del Duomo (Pisa)
Roskilde Cathedral
Speyer Cathedral
Vatican City

I would like to argue in favour for this one, and at least place it into the "Maybe"-category. It does have a very specific, non-European architectural style. Many other Latin American cathedrals are Churrigueresque, a totally different style.

I personally don't like Chartres Cathedral, its long history of construction that put all Gothic Styles from Early, High and Late Gothic make the overall design very strange, but if we need one site to represent all Gothic development, Chartres is a perfect choice. But if we want a masterpiece of certain period then I will go with Amiens or Reims Cathedral.


Not my favorite, but we need a good example of "Brick" Cathedral.


Not sure about this. The famous part is its leaning tower not the cathedral which is actually very beautiful.

Vatican City (Religious Significance/Art)
Aachen Cathedral (persuaded by meltwaterfalls)
Piazza del Duomo (Pisa) (Iconic)

My selection:

Canterbury
Piazza del Duomo (Pisa)
Vatican City
Westminster

Very true that the tower is the most famous part, though I was genuinely surprised when I visited just how beautiful the whole architectural ensemble was, shame the dodgy foundations take precedence.

Great explanations overall, meltwaterfalls! I would however disagree with your comments on the 2 above - from a historic perspective, both are Catholic cathedrals (Canterbury rebuilt in Gothic style in 1174; Roskilde in the 12th & 13th centuries - both according to Wikipedia). So in my opinion Protestantism cannot be a reason for adding them. For that, we might have to consider less iconic sites, I'm afraid - like the Luther memorial sites or the Churches of Peace in Poland...


Not sure whether we have discussed it yet, but Lübeck might fit the bill - in addition to being the most relevant Hanseatic town.