V/A+ 더군요.

It is attached to the stem of an action verb or descriptive verb to deliver what the speaker has seen, heard, or experienced in the past. It cannot be used for the behavior of the speaker himself.

몸이 안 좋아서 병원에 갔는데 의사가 당장 담배를 끊어야 한다고 경고하더군요.
I went to the hospital because I wasn’t feeling well, and the doctor warned me that I should quit smoking right away.

지난주에 제주도에 가서 한라산에 올라갔는데 생각했던 것보다 훨씬 아름답더군요.
I went to Jeju Island last week and climbed Mt. Halla. It was much more beautiful than I thought.

제가 졸업한 초등학교에 오랜만에 다시 가 봤는데 모든 것이 그대로 남아 있더군요.
I visited the elementary school I graduated from after a long time, and everything remained the same.

Conversation:

저것이 7세기 경 신라에서 천체를 관측하던 첨성대예요.
That’s the Cheomseongdae, which was used to observe celestial bodies in Silla around the 7th century.

경주를 소개하는 자료마다 첨성대는 늘 빠지지 않고 있더군요. 역사적 가치가 높은가 봐요.
I found every piece of material that introduces Kyeongju includes Cheomseongdae. I guess it has a high historical value.

네, 동양에 현존하는 천문관측대 중에서 가장 오래됐다고 해요.
Yes, it’s the oldest astronomical observatory in existence in the East.

아주 견고하게 지어졌나 봐요. 그런데 별을 보기에는 좀 낮아 보이지 않아요?
It must be built solid. But doesn’t it look a little low to see the stars?

맞아요. 요즘에는 첨성대가 천문대가 아니라 하늘에 제사를 지내던 제단이었다는 학설도 제기되고 있어요.
You are right. There are theories that Cheomseongdae was not an observatory, but an altar to heaven these days.

그렇군요. 고대에는 자연 현상을 보고 국가의 길흉을 점쳤으니까 그럴 가능성도 있겠어요.
I see. It’s possible because, in ancient times, people looked at natural phenomena to predict the fortune of a country.

Related words
천체 celestial body
관측 observe
현존 in existence
천문대 astronomical observatory
제단 altar
학설 theory
고대 ancient
길흉 fortune
점치다 tell one’s fortune, make a guess

Source: Yonsei University. Korean Language Institute