I came across the Web site of the "Comision del Patrimonio Cultural del Nacion" aka "Patrimonio Uruguay" (an arm of the Ministry of Education and Culture) the other day. It publishes an annual magazine ("Patrimonio" - in Spanish of course!) with a Web copy which includes articles on Uruguayan WHS and T List sites (as well as on all sorts of other Uruguayan cultural matters both tangible and non tangible)- it might be of interest so I have started a separate topic for this country which has recently become "active" again on the WHS front and will be hoping for a new inscription in the form of Fray Bentos in 2015!

The organisation's Web site - http://www.patrimoniouruguay.gub.uy/

Patrimonio 1 (2011) - contains an article "Aspiraciones al Listado de Patrimonio Mundial" about Uruguay's T List created in 2010 with descriptions/photos of most of the chosen sites - http://www.patrimoniouruguay.gub.uy/innovaportal/file/33821/1/revista-patrimonio-nro1 .pdf

Patrimonio 2 (2012) - Montevideo architecture and old city remains. Also - Colonia del Sacramento
http://www.patrimoniouruguay.gub.uy/innovaportal/file/33821/1/revista-patrimonio-nro2 .pdf

Patrimonio 3 (2013) - Fray Bentos progress towards inscription
http://www.patrimoniouruguay.gub.uy/innovaportal/file/55571/1/patrimonio3_web.pdf

Patrimonio 4 (2014) -doesn't appear to have been published yet!!

Wondering whether someone recently has researched the scope of the "Architecture Moderne du XX siècle de la Ville de Montevideo" TWHS.
In his 2 reviews, Assif seems to think that the Art Deco in the center is not included, but I can't see why it wouldn't be (only when they will focus on a specific neighbourhood, around Park Batllo y Ordonez, similar to the scoping of the White City of Tel Aviv).

The official site description is vague, but seems to cover about anything in the city of Montevideo produced between the years 1915 and 1965. Unfortunately, the link given above by Solivagant to the articles doesn't work anymore for me - UPDATE: found its new web location (#1 shows Palacio Lapido as the photo for this TWHS, so Art Deco is included).

Looking at the inventory of monuments in Montevideo (summarized at wiki as well with some pics), and then filtering the ones from ca. 1920-1950, I see for example the following ones:
Edificio Centenario
Edificio Bartolomé Mitre
Edificio Juncal
Palacio de la Luz
Palacio Lapido
Casa Strauch

Art Deco Montevideo overview here. Featured buildings are:
o Casa Vilamajó
o Edificio Centenario
o Edificio Lapido
o Palacio Salvo
o Edificio El Indio
o Edificio Mariposas
o Edificio Tapié
o Palacio New York

(I see many neoclassical buildings from that period as well, I assume these are not included)

A nomination dossier is in the making for Isla de Flores. We have it as a nomination for 2025. According to the news article below, they tried to submit in 2023, but apparently, they didn't make the Feb 1 cut (as it's not on the list for 2024). When you read about the island on the web, many people lament its poor state of conservation, so it still seems to need a lot of work.

It will be a mixed nomination and it is a site of memory - so I guess a high chance of inscription.
https://www-elpais-com-uy.translate.goog/vida-actual/isla-de-flores-un-tesoro-nacional-que-es-paraiso-y-fue-purgatorio?_x_tr_sl=es&_x_tr_tl=en&_x_tr_hl=nl&_x_tr_pto=wapp

I have been looking for a tour there, but it appears that the island is closed at the moment due to bird flu?

I failed at finding a tour when I was there and couldn't find an alternative way of visiting during my stay. However, I think I still have the phone numbers of a bunch of boat owners a guy gave me at the marina. I can try to find them if you're interested.

Nautitour SRL is the one that normally goes there, but they're the ones saying it is closed
I will contact them a bit closer to my arrival date (late February). Maybe the seals and the birds will be better by then..

I just finished a trip to Uruguay (as part of my longer Miami to Patagonia journey) and would like to share some public transport info to cover all WHS.

Montevideo – Church of Atlantida
As said in the reviews, there are plenty of buses from for example Tres Cruces bus station that will drop you off by the road at the entrance road to Estacion Atlantida. From there it is a 3km walk. I hiked up on the sand road and on the return took the main road (there's a foot and bike path next to it). Both roads have little shade, but there are some stalls where you can buy cool drinks. The buses from Tres Cruces usually are the nicer ones, so the trip out there cost 276 pesos while on the return I caught a less fancy one for 123 pesos which took me all the way to the historic center of Montevideo.

Alternatively, if you time it well, you could also get on a direct bus to Estacion Atlantida from the Baltasar Brum station in Montevideo and thus skip the walk. Buses 710 and C5. These buses are geared to local commuters so go mostly in the early mornings, but the church is open at 8 am already as well so it could be an option. They even pass the airport so you could go from there directly.

Montevideo – Fray Bentos
Fairly easy with CUT from Tres Cruces, nice modern bus (but without phone charger). Buses at 8, 13 and 17 (and some later ones). Took me 4.5 hours on a half-empty bus. Bought the ticket a day before but that wasn't necessary.

Fray Bentos – Colonia
Grupo Agencia does this twice a day, 9.45 and 19.45. Takes 3h50. Again, bought the ticket the day before and got seat 33. The bus was not full at departure but at certain stretches (mostly around the city of Mercedes) it got busy and people had to stand. Tickets can also be bought via the Grupo Agencia website.