Mahendraparvata (Mountain of Indra) may have been the first capital city of the Khmer Empire. Having lost the tv remote when a show I want to watch is coming on, I can appreciate the thrill of the of these archiologists on this discovery. I think these photographs in the article are Angor Wat, but another lost city is always welcome for Camobodian archiology research and tourism.
That shows how dense the forest is in Phnom Kulen National Park (that they did not find this lost city sooner). Note how the extent of argriculture and development both around Angkor Wat and Phnom Kulen. There is not dense uninterrupted forest in most of Cambodia.
Smithsonian: Finding Mahendraparvata