Upon entering the castle is a large circular room bordered by twin staircases that curve along the outer walls, leading up to the First Floor. The floor of the rotunda is composed of Calacatta marble, and was designed with loitering in mind, as numerous cushioned benches and tables, set out with games such as wizard's chess and exploding snap, litter the space. Doors underneath each staircase lead out into the rest of the Ground Floor, with the Assembly Hall and Library to the east, and the Dining Hall and Portiport to the west. A large, open archway in the north leads out into the Courtyard, and the sounds of a gentle breeze and birdsong provide a gentle backdrop to the space.

A scuffed and faded plaque by the door indicates that this room was once called the Half-Moon Ballroom, likely in reference to its semi-circle shape, though these days the room is known simply as the Assembly Hall. A large stage stands in the middle of the wood-panelled room along the single straight wall, with a large, ornate portrait of each founder resting prominently, center stage. Four sets of wooden benches curve around it, one section for each house. This room is largely used for the Sorting Ceremony, and as a gathering space for Penwick's theater and debate clubs, respectively, though it is also used for its traditional purpose as a ballroom on occasion, during which the benches are often simply floated up to the ceiling for storage, acting as some of the most peculiar balloons that you've ever seen. Dance lessons are held here biannually for all interested parties third-year and above, with one session in January and one session in May.

The courtyard forms a rectangular quad covered in neatly trimmed grass, cut through by two broad walkways that meet in the centre. A low circular plinth marks the crossing point, a convenient place to sit or dump bags between lessons. Atop the plinth lies the Celestial Sundial, a polished brass gnomon whose shadow is seemingly not tied to the sun at all, as day and night it warps across the yard and touches stone etchings that represent the hour, date, month, year, and lunar phase. A colonnade of stone columns provides shelter on the perimeter of the courtyard, where seasonal banners hang and flutter.

Behind a grand pair of oak doors that require some effort to push open, Penwick's library stretches far deeper than it appears at first glance. The main chamber is long and vaulted, lined by tall bookshelves and stone columns that disappear into the arched ceiling above. Books reshelve themselves with the occasional "thud", and the occasional whisper can be heard from the small alcoves that dot the perimeter of the chamber. Tall stained-glass windows filter in light into muted jewel tones, creating a spectacular display at sunrise for those early birds willing to catch it. A wide reference table dominates the centre of the main chamber, surrounded by smaller study desks. Sections are clearly labelled in Latin, Welsh and English.
In the back of the room, grand spiral staircases flank the librarian's desk. To the left, the shorter staircase leads to a mezzanine of older books chained to heavy desks. These books are not necessarily restricted, but are dangerous enough to warrant not removing them from the library. To the right, a high staircase leads to the upper levels of the library; the restricted sections, which require written permission from a professor to enter.

The Portiport is the castle's heart of activity, a large white-marbled rotunda. At the center of the room looms a rather pompous statue of Griffith Virell, Penwick's first Headmaster, depicted in an almost cliché heroic pose. Five large archways are carved into the rounded walls of the room, a Roman numeral etched above them. Step through an arch, and you emerge at that floor’s landing with no need to take the stairs. Similar arches can be found on the landing of each floor that transport back to the Portiport.
There are stairs in the castle, but their steep, dizzying climbs seem more like a punishment than a form of transportation. Professors insist they remain for emergencies, students insist they remain as a cruel joke.
The Portiport is noisy at every change of class, students spilling through its arches like floodgates. And while no one ever gets lost here, there are whispered tales of students arriving a floor too high, usually after offending Griffith’s statue.

The first thing to notice in the Dining Hall, aside from the smell of food, is the intricate fresco on the ceiling, telling the story of Camelot. Below, black-and-white tiles contrast with dark wooden walls, where stairs lead to small mezzanines overlooking the main floor. Light streams through high windows, glinting off tiles, polished wood, and brass fixtures.
Buffet tables line the hall, always brimming with a rotating array of dishes for breakfast, lunch, and dinner. Students wave between the tables, trays in hand, selecting their meals before finding a seat. Mahogany circular tables fill the hall, each surrounded by matching sturdy chairs, accommodating the majority of the student body. Mezzanine seating offers a bird’s-eye view of the activity below, and are often claimed by students with a reputation for popularity or influence.
At the end of each meal, a soft chime resonates through the hall, reminding students to quickly finish their meals before returning to class or their common rooms.

The entrance to House Floranti is actually found outside the castle, much to the dismay of students on rainy days. From the castle grounds, it looks like nothing more than a thicket of ash and oak, their branches twined so densely no path could possibly exist between them. Students who belong here, however, know the trick. At certain angles, the sun, moon, or the sky itself on cloudy days, glints off a knot in a tree’s bark. When the student steps beneath that shifting point of light, the grove rearranges, revealing a narrow, winding path toward the Floranti commons. The effect is fleeting; move too slowly, and the illusion returns, leaving only ordinary woodland behind.
The path ends in a courtyard of mossy stones and creeping ivy, where the glass doors and walls of the Floranti commons rise like a gleaming conservatory.