Best "unknown" Places in Paris

Much depends on what you would consider "fun to see/do". Give us some clues, as well as what is already on your list, to spare us all repetitious suggestions. Are you three guys, three women? Are you young and vigorous, or a little on the slower side? In other words, details, please.

Edit: There are no "unknown places" in Paris.

If we were to give you a list of our researched places "unknown" in Paris, they wouldn't remain unknown would they?

Head in a direction away from the 1st and see what you come up with. It would be 'unknown' and unresearched for you. Or, just because I like it, look at the website Atlas Obscura. It lists minor or 'different' places and events around the world. Plug in 'Paris' and see what it has.

You can check out this website that comes up when I googled 'off the beaten path in Paris'. That is something I do when starting to research the more untouristy sights in a new city. Also, if you like nature spots, take a look at the book "Hidden Gardens of Paris" by Susan Cahill.

Anyone have any interest in Art Nouveau architecture? There are some Jules Lavirotte buildings in the 7th.

https://en.wikipedia.org/wiki/Jules_Lavirotte

https://www.parisperfect.com/blog/2011/03/art-nouveau-7th-arrondissement/
(Sorry, this link goes to a blog with a lot of advertisements...)

Thanks for the memories, Pam!

Debbie,
I was in Paris mid-April 2018 and stayed on Ile St-Louis in a small charming hotel. We loved the island, filled with restaurants, shops and little groceries, cafes with outdoor seating. I will share some of the things we did that were not the top sights.
Paris Walks- We took the Hemingway walk with a thoroughly interesting and entertaining guide. This walk took us through much of the Latin Quarter. Paris Walks has many options to choose from.
Pere LaChaise Cemetery where many famous people are buried (we didn’t do this as my friend couldn’t manage it with the heat in the mid-80’s). It is on my list for next time.

If you all like Monet, go to the Marmottan Musee, a house museum established by Paul Marmottan who collected Monet’s paintings and other Impressionists’ art.

Also try Jacquemart-Andre Museum, another elegant house museum that often has art exhibits going on. A fabulous tea room for tea/coffee and dessert!

I love the Cluny Museum of medieval art, stained glass, sculpture and the famous Unicorn Tapestries! I went to a beautiful concert there in the evening.

Just a few ideas I have enjoyed, I have many more on my list for the future.

Friends have raved about the Atelier des Lumieres lights in Paris, apparently a digital art museum. I’m sure it’s popular so you will want to investigate getting advance tickets.

While not unknown, the most overlooked amazing site in Paris is Basilica St. Denis on the metro line 13 which houses the tombs of the kings of France.
https://janettravels.wordpress.com/2010/10/26/confronting-mortality-at-st-denis/
I'll bet none of your friends will have been there.

I’ll add to the list:

Cognacq-Jay Museum in the Marais. Small, free museum displaying a collection of 18th century art owned by Ernest Cognacq and his wife Marie-Louise Jay.

Musee Nissim de Camondo. Furnished home owned by a Jewish family early 1900’s. Beautifully furnished and very interesting family history. Near Park Monceau.

If you go to the d'Orsay museum you'll be near the fascinatingly bizarre taxidermy/institute for natural sciences shop called Deyrolle at 46 rue du Bac https://deyrolle.com/

I second the idea of Deyrolle!

I recommend the Atelier des Lumières. The museum takes artists and turn their works into digital art paired with music. We were lucky to see the Klimt exhibit this past November. We are going back to Paris this year, and we will be going to see the Van Gogh exhibit. It really is hard to describe how beautiful the exhibitions are. You can see what it is like here: https://www.atelier-lumieres.com/

Ellen F mentioned Park Monceau. If you enjoy park spaces, Monceau is a good one to visit. I bet it will be beautiful in the spring.

Not sure if this is your thing or not, but the Opera Garnrier has a Phantom of the Opera escape room game that looks interesting:
https://www.operadeparis.fr/en/visits/palais-garnier/individuals-2/the-life-size-escape-game-in-the-heart-of-palais-garnier

If you have an interest in science, The Pasteur Institute has a museum dedicated to Louis Pasteur. It includes his original lab equipment and notebooks of his work, his apartment and crypt.
https://www.pasteurfoundation.org/about/pasteur-museum

My favorite is Arenes de Lutece. It's a little park not far from the Latin Quarter that is built around the ruins of a Roman era arena (from when Paris was called Lutetia by the Romans). I like to buy a to go lunch from a local grocery or boulangerie, generally a sandwich and drink, sit in the nearly 2,000 year old stands with other Parisiens eating their lunches while watching children play football or older men play boules on the floor of the arena.

Canal St. Martin is a good place to walk, especially on a weekend afternoon. It's quirky and mostly local. There is often live music or a DJ at Villemin Garden. I wouldn't suggest taking a canal cruise there though, the boats are slower than walking and take forever to get through the locks. It's better to walk and pause to watch boats go through them. Further up the canal, just before the Bassin, however, there is a giant tent camp of immigrants. It didn't seem dangerous but also not attractive.

Debbie,
What part of Paris are you planning to stay? I usually select my hotel in an area that is near sights I want to take in. The flowers will be in full bloom the first week of May.
I haven't seen anyone suggest Giverny and Monet's Gardens even though it is not "unknown". It is one of my favorite places to visit. I was in Paris in April 2018 and we saw Giverny on a Sunday (we had no choice, it was our only free day) which is usually mobbed on the weekends. If you do go, try to go on a weekday.
Enjoy your trip!

I would go to the 20th Arrond. where chances are you just might run into no tourists at all, at least international tourists...you just might be the only one..literally.

I'll jump on with everyone who recommended Atelier des Lumières. Really enjoyed the Klimt show I saw, and the building is just a few blocks away from Pere Lachaise - which isn't unknown by any stretch, but it makes sense to do them together.