Constanze's Workshop is Constanze's secret workshop in which she can work on her various projects without bringing the attention of Luna Nova's staff.
The underground workshop comprised of the main chamber and an underground hangar for Stanship. The former serves as the main working space and thus has paraphernalia Constanze needs for her project including a bookshelf for blueprints, notes, and books alike; a large drawing table, a toolbox, and a personal computer. Interestingly, the workshop also has a large cage for containing intruders and other riffraff.
While it appeared that she built the workshop beneath Luna Nova Academy itself, it is suggested that this working space is in fact located somewhere else, with the academy only served to hide one of its secret entrances (her bed). This further supported by the lengthy course of the cart Akko rides on while inadvertently discovering the aforementioned secret passage and how it also reaches River Thames, suggesting the workshop located somewhere between either.
The workshop may have been built sometime during her early days of enrollment at Luna Nova, if not prior, so she can work on her inventions as well as storing her equipment and weapons without getting caught by professors.