St. Georges Cathedral is one of Guyana's 3 T-list entries located in the capital Georgetown. It is its major landmark, and the most likely candidate of them all I guess.
It's a huge wooden cathedral, rivalling the one in neighbouring Paramaribo for the title of tallest wooden structure in South America or even in the world. It dates from the late 19th century, and though it is a National Monument it is still very much in active use.
The exterior is the most picturesque part, it is located in the center of a "traffic island" and therefore can be viewed well from all sides. A comparison to the one in Paramaribo is tempting of course, and I must say I prefer this one in Georgetown. The historic wooden monuments of Paramaribo are in much better shape though.
The interior is nicer too, although it has a bit of an odd collection of decorations.
Guyana has no WHS to date, and had its no.1 tourist attraction Kaieteur Falls withdrawn in 2001. Maybe they should try again with that one: the policy nowadays seems that every country should get its WHS. The Falls are in every Top 10 List of waterfalls around the world, and are located in Guyana's only National Park. I think it would be a huge stretch to get this gothic cathedral included in the WH List, as well as any other of the current sites on Tentative List.