It is the eponymous location mentioned in the title of the series, and it is the means by which Xavier, Yadina and Brad travel backward in time to meet historical figures during their childhoods.
They appear to think of it like a sentient entity. Like, for example in I Am Harry Houdini, Xavier mentions "I wonder who the Secret Museum will send us to meet", indicating it makes the choice based upon what lessons they need to learn.
In every episode, it presents the kids with an artifact from a historical hero, and sends them back in time to meet the hero with the help of Berby.
Xavier and Yadina's parents own and operate the museum atop the secret one. Xavier and Yadina live there. In I Am Mary Shelley, Brad mentions that they live there. In I Am Charles Dickens, Yadina's room is shown, and the kids head to the Secret Museum from there. In I Am Neil Armstrong, the kitchen is shown. In I Am Marie Owens, Xavier calls it "our family museum".
The kids access the Secret Museum through unconventional means, such as via:
- Painting: I Am Johann Sebastian Bach, I Am Harry Houdini, I Am Alexander Graham Bell, I Am Tomioka Tessai, I Am Julia Child, I Am Abigail Adams, I Am Eleanor Roosevelt, I Am Marie Owens
- Tornado: I Am Marie Curie, I Am Isaac Newton, I Am Zora Neale Hurston, We Are the Wright Brothers
- Egyptian Exhibit: I Am Mary Shelley, I Am Amelia Earhart, I Am Cleopatra, I Am Mark Twain, I Am Mary Leakey
- Grandfather Clock: I Am Helen Keller, I Am Winston Churchill, I Am Charles Dickens, I Am Anna Pavlova
- Dinosaur Mouth: I Am Florence Nightingale, I Am Leonardo da Vinci, I Am George Washington, I Am Neil Armstrong, I Am Jackie Robinson, I Am Theodore Roosevelt
- Chinese Throne: I Am George Washington Carver, I Am Golda Meir, I Am Catherine the Great, We Are the Bronte Sisters, I Am Alexander Hamilton
- Umbrella: I Am Lou Gehrig
They don't enter the Secret Museum in I Am Susan B. Anthony, because they're already there.
In Xavier Riddle and the Secret Movie: I Am Madam President, Xavier, Yadina, and Brad enters an Egyptian Tomb, then the plane, the dinosaurs, and the other painting as a portal.
- question mark landing
- cubbies containing artifacts
- holographic display
- portals through time and space
- Johann Sebastian Bach's sheet music
- Marie Curie's chemist glass
- Mary Shelley's feather pen
- Harry Houdini's key
- Helen Keller's braille book
- Alexander Graham Bell's paper
- Florence Nightingale's lantern
- George Washington Carver's flower
- Leonardo da Vinci's journal
- Amelia Earhart's pilot cap
- Isaac Newton's windmill
- Golda Meir's poster
- Winston Churchill's bowtie
- Cleopatra's coin
- Catherine the Great's crown
- Tomioka Tessai's paintbrush
- George Washington's hat
- Susan B. Anthony's shawl
- Zora Neale Hurston's cornshuck doll
- Charles Dickens' inkwell
- Wright Brothers' toy helicopter
- Bronte Sisters' three books
- Mark Twain's paintbrush
- Abigail Adams' ribbon
- Julia Child's spoon
- Neil Armstrong's space helmet
- Jackie Robinson's baseball
- Anna Pavlova's ballet shoes
- Mary Leakey's brush
- Alexander Hamilton's coin
- Theodore Roosevelt's hat
- Eleanor Roosevelt's microphone
- Lou Gehrig's baseball glove
- Marie Owens' police badge
- ↑ 7 December 2019 tweet "Hi MJ, great question! The museum is owned & operated by Xavier & Yadina’s family, so they basically have the run of the place & are the only ones who know about the secret museum within. We are checking with the creative team about whether the kids live there - will let you know"