Gatnyang is a cheese cat in a gat, the black horsehair hat Korean scholars wore, with a plum-blossom fan in one paw. Tell her what you like and how long you have, and she plans a Seoul course from half a day to five days, then walks you through it picture by picture before you go.
Every place in a course is researched from official pages and recent Korean and English videos and blogs, and each one shows the date it was last checked. Courses are put together by fixed rules, not generated on the fly, so the same answers always give the same course.
Photos come from Wikimedia Commons under open licenses and are credited on each picture. The site is free, with no ads and nothing to sell.