I saw an answer to an exercise on EnglishPage:
"Travel Magazine" did an extremely interesting article on the world's most amazing buildings. If I remember correctly, the first building on the list was (/) Angkor Wat, a beautiful temple in (/) Cambodia. And the second was the Pyramid of Khufu in (/) Egypt.
(/) indicates no article.
I think Angkor Wat is a great architectural achievement, so it should have article the, like the Pyramid. Am I right?
Angkor Wat is a temple complex, not a single temple, so we can treat it like a city name. We could also say "the Angkor Wat temple", although I think that would tend to be the way tourists that don't understand that Angkor Wat is actually many temples would refer to it.
The Khufu Pyramid is a singular thing because even though there is a "complex" of buildings around the pyramid, those buildings aren't "great pyramids". The great pyramid itself is what people are thinking of when they refer to that place, so we use the definite article.
There is no clear cut rule however, which makes it difficult to explain why we choose to use the definite article in some cases and leave it off in others. There is some advice in this BBC article "The with place names: rules and exceptions". The article says
When it comes to buildings, it is more difficult to see a pattern emerging. It is more a case of Learn It.
Temples, castles and palaces do not generally take an article.(with some exceptions).
The is used to refer to the pyramid of Khufu because it is ,I assume ,the only pyramid there or because it is being made specific by its location (Khufu )compared to a pyramid elsewhere in Egypt.
