In the games, the Gym is located behind the Nacrene Museum. It has a library and a downstairs, hidden room, in which Lenora is located. The library contains numerous large bookshelves; 5 of these bookshelves have small step ladders in front of them. When the player walks up these ladders, the player can interact with a book. The books have various memos inside them; the player must locate them one after the other and solve them. After finding all of them, one of the bookshelves will move aside, letting the player reach the lower room.
The lower room has two glass cases with exhibits on display. Lenora awaits challengers in the middle of the room. At the back, there are several more bookshelves along with the Gym logo.
In the Anime
The Nacrene Gym is located inside the Nacrene Museum. The Museum is a historical building and features a large range of exhibits such as fossils, skeletons, knight's armor and tombs. Hawes is the vice-curator of the museum. Near the back is a library where a code is needed in order to get to another library with a diverse range of different books. Here, Lenora will test the Trainer to see what type of Trainer they are. She will point to the book that reveals the staircase to the Gym, and the Trainer, based on how they read Lenora's actions, will either try to read it or search for another book.
Once finding the correct book, they head downstairs to the battlefield. The battlefield has a normal, basic terrain. In A Night in the Nacrene City Museum! a Yamask was causing havoc in the museum.
Ash challenged Lenora in The Battle According to Lenora! where he lost. Ash finally won in Rematch at the Nacrene Museum!, earning himself the Basic Badge.
In the Manga
Black went to Nacrene City to challenge Lenora to a Gym Battle.