A/V/N + 었던 것 같다 is used to recall a past experience or to speculate on a general past ("in the olden days..."). It suggests that your memory is vague and you don't remember exactly:
묵었던 호텔 중에서 싱가포르의 마리나 베이 샌즈가 가장 아름다웠던 것 같아요.
I think Marina Bay Sands in Singapore was the most beautiful hotel I've ever stayed in.
작년 봄이 더 시원했던 것 같아요.
I think spring was cooler last year.
그 중식당에서는 돼지고기가 맛있었던 것 같아요.
I remember the pork was delicious at the Chinese restaurant.
인터넷을 사용하기 이전에는 생활이 더 힘들었던 것 같아요.
I think life was harder before the Internet.
몇 년 전에 여기에는 도서관이 있었던 것 같아요.
I think there was a library here a few years ago.
마지막으로 그 지역에 있었을 때 일본 식당이 벌써 폐쇄되었던 것 같아요.
The last time I was in that area, I think the Japanese restaurant had already shut down.
친구의 얼굴을 봤을 때 울었던 것 같아요.
When I saw my friend's face I think he'd been crying.
아까 백화점을 지나갔는데 문이 닫혔던 것 같아요.
I passed by the department store earlier and I think it was closed.
21살 생일을 위해 부모님께서 기타를 사주었던 것 같아요.
I think my parents bought me a guitar for my 21st birthday.
저 여자는 언제 만났던 것 같아요.
I think I've met that woman before...
잘 기억은 안 나지만 한국에 처음 왔던 날에는 서울 한강공원에 갔던 것 같아요.
I don't remember exactly, but I think I went to Hangang Park in Seoul on my first day in Korea.
예전에 여기에서 사진을 찍었던 것 같아요.
I think I took a picture here before.
제일 처음 먹었던 한국 음식은 삼계탕이었던 것 같아요.
I think the first Korean food I ate was samgyetang.
어렸을때 집에서 학교까지 버스 요금이 20펜스쯤이었던 것 같아요!
I think the bus fare from home to school was about 20p when I was young!
어렸을 때는 장난치기 좋아하는 학생이었던 것 같아요.
I think I was a mischievous student when I was younger.
바레인에 살았을 때 이웃이 독일 사람이었던 것 같아요.
When I lived in Bahrain I think my neighbours were German.