In Warframe, the Leverian is like an exhibit that is operated by a character called Drusus Leverian. They take the form of a gallery that you can walk around, looking at objects related to a particular Warframe, while Drusus gives you a narrated history of the Warframe.
How To Access The Leverian
When looking at a Warframe in the Codex, which you can access from the relevant console in your ship, you may notice the Leverian button in the bottom right of the screen. Clicking this button brings you to the Leverian itself. You can also access it via the Warframe’s page in the Market.
At the moment, the number of Leverian entries appears to be limited to just Gauss and his signature weapons. But more may get added in the future. There is also a small donation box at the start of the gallery that you can donate too. At the moment it is unknown if there is a further mechanic behind this, or if it is just similar to many museums in real life.
After you enter the Leverian, you can walk between the displays, hitting the interact button to listen to Drusus impart his knowledge about the history of the Warframe.