At the northwestern corner of the Brig-Wallis Preparatory School campus sits the wing of the Quad known as Merchant House. During the 17th and 18th Centuries, this part of the campus grounds had served a local merchant as both business site (with storefront) and family residence. According to the building's original functionality, the ground floor was used to conduct business of the day (there were, at various times, multiple retail stores on the ground floor). A spacious, high-ceilinged first floor contained the merchant family's living quarters. It included kitchens, living area, library, and master bedrooms. A second floor, beneath the rafters of the roof line, contained unheated, unplumbed, dormitory-style sleeping areas for the children and guests. Beneath the ground floor lay a fully functional basement which was used for dry storage, both personal and mercantile. The basement had below-ground road-side access near its west end. The west end is also where access ports for coal and other heating materials existed for the various basement-level heating systems used over the course of the two centuries. The property, which measured slightly more than an acre and cast a nearly-square rectangular shape to the south of Polenstrasse, grading up the slight incline of the subAlpine foothills toward Simplon Pass, contained a single outbuilding: a three-sided storage barn--more of a large lean-to--which served to shelter animals, transportation aides, and mercantile overflow.
In the third decade of the nineteenth century, Merchant House went through a cosmetic remodel to strengthen its core as well as to modernize its exteriors. On its Quad-facing exterior it was made to match the Collegiate Gothic styles of Aubrey, Châtelaine, and Engineering Halls while the previous structural organization remained fairly unaltered. There remained a full basement, which continued to be used for storage as it had by the merchant family, but was now shored up with new columns and beams and poured concrete floors and walls. The outside access to the basement level from Polenstraße was sealed, filled, and virtually erased from memory.
The modern-day concrete and stone u-shaped switchback staircase at the building's east end was installed in 1848, preceding the planned construction of the headmaster's residential and office spaces in the Flamboyant Gothic Gatehouse built over the campus's Polentrasse entrance.
The current apportionment of space provides for two squash courts and an archery range in the basement as well as the building's boiler room heating system. Above ground, on the rez-de-chaussée, there exists four three-room apartments with individual bathrooms serving as teacher's quarters. On the first floor there is one six-bedroom full-floor suite which is designated for use by third-year students. The second floor contains four small bedroom-efficiencies, two on each side of the building, with a shared bathroom between each of the pairs of rooms. These latter rooms were generally designated for use for guests and upperclassmen (fourth year students).
With the completion of the campus's self-contained quadrangular enclosure in 1810, all traces and signs of external access points to/from Merchant House were removed. Other than emergency window escape routes, and the small coal-loading portal in the coal cellar of the building's west end, next to the boiler (later sealed with the conversion to oil, and, later, natural gas), the only ingress and egress points to the building were through the Quad-side staircase and then to Polenstrasse through the main entrance beneath the Gatehouse.