The building resembles a Viking ship. Inside, it contains ancient artifacts, and other relics, such as formerly the Atlantean Amulet, which SpongeBob and Patrick completed to get a trip to the underwater city of Atlantis. Mr. Krabs took admission there (unofficially). Squidward was seen painting pictures that relate to Atlantis. It includes many artifacts, art, historical items, and many other things of ancient history.
Role in SpongeBob
"Atlantis SquarePantis" and SpongeBob's Atlantis SquarePantis
In both versions, Mr. Krabs tries to scam a customer out of money and Squidward puts the pieces of the Atlantean Amulet together, which summons the Sea Ship Atlantis that will take Mr. Krabs, Squidward, Patrick, SpongeBob, Sandy, and Plankton to Atlantis.
The customer being scammed is Miss Shell and SpongeBob finds Squidward almost immediately after they enter. There is also a whole scene that explains what Atlantis is.
SpongeBob's Atlantis SquarePantis
There is a whole level in the Bikini Bottom Museum.
"Are You Happy Now?"
SpongeBob takes Squidward here to try to help Squidward to have a best memory. Squidward finds a statue of his in the museum. He is happy. Soon, Fiasco burns the statue. This makes Squidward sad.
The museum was bigger than it is now, but Patrick sat on a mine and part of it got destroyed.