The House of Curios is found in the Fields of Misery. An outdoor area of Act I, it is sometimes found in a small random map area called Lonely Dwelling (~5% spawn chance). Inside you'll find Adenah the Curio Vendor and Adenah's Jottings.
The player(s) must start on the quest: Act 1, Chapter 5, Part 2. It will save a checkpoint upon entering the Fields Of Misery which you can leave and resume from. It also may be bugged where you have to start from here or you will never find it.
If one sees anything OTHER than the following, use a TP, leave game, resume, recycle:
Following these steps, one should get the House of Curious quickly.