Glasshouses/greenhouses: Kew gardens Amsterdam: Hortus Botanicus Schönbrunn: das grosse Palmenhaus Wien: Burggarten
>> these are too close to Botanical Gardens, of which we already have a connection

Largest non-capitals
>> too far-fetched, too long list

Railway – Everglades
>> please clarify

Built in the 18th century
Wooden Churches Slovakia - about half of them were built in the 18th Century.
>> some are 16, some 17, some 18thcentury; which period is the most significant (or which example)

Conical roofs
Conceigerie, Paris, France
>> is this within the borders of the WHS?

Railways
Banska Stiavnica: Old Railway Station
>> Not in AB evaluation, only minor feature I guess

(3151) Cemeteries
Banska Stiavnica: some cemeteries near the city centre
>> Not in AB evaluation, only minor feature I guess

(2562) Market Halls
Valetta
>> please clarify significance

(2563) Theatres
Valetta: ruins of the opera
>> only ruins? still any significance?

Re: Largest non capitals - what I meant was that we have a connection located in a capital city but it misses cities which are the largest in a country but are not the national capitals. There aren't many such examples. I could only come up with four: Tel Aviv, Sydney, Istanbul and Essen (Ruhr).

Re: Greenhouses - Palmenhaus in Vienna is near Schoenbrunn zoo and the Butterfly House is near the Burg Palace. Both are far away from the botanical garden which is near Belveder.

Re: Theatres: http://en.wikipedia.org/wiki/Royal_Opera_House,_Valletta

Conceigerie is located on the Ill de la cite, next to the saine, so definitely within the border of the WHS.

I did not mean "close" in distance, but in "the same kind of" (all Botanical gardens will have a greenhouse I think)

There's no clear connection to WHS (Sydney is no WHS, only the Opera House is), connection is too trivial. Also Essen is not Germany's largest city.

For Banska Stiavnica there is an official list of important technical monuments inside the WHS. All could be potentially included in the connections. Also the railway station is included... http://www.banskastiavnica.sk/en/obcan/unesco/list-of-monuments-1.html

Hyde Park Barracks is within the City of Sydney and metropolitan Sydney incorporates Old Government House in Parramatta and Cockatoo Island (all part of the convict sites serial listing). But Large Cities is a tricky connection because their centres are invarably too large to be listed in and of themselves.