When it came time for Hernan Rios to renovate his apartment inside a 1968 Louis Herman De Koninck building, he reached out to Matteo Colombo and Andrea Serboli's Barcelona-based firm CaSA. Located in the center of Brussels, Belgium, the Brutalist structure is now the home of a newly bright and crisp interior inspired by the über-clean simplicity of European hotels. A graphic designer by trade, Rios traded embellishment for sparcity and though his environment may not be meant for everyone, it's tailormade for him. "I'm a maniacal perfectionist, and we were shooting for smooth walls, near-zero moldings, ceiling reveals along the window walls and different volumes that all had to measure up perfectly. Every line had to be straight, aligned with other components, and cleanly executed," he says. "Additionally, we suffer from rather grim winters, so considerable attention was given to finding solutions that would allow the maximum amount of light to penetrate as deeply into the interiors as possible." No part of the Spartan, 1,055-square-foot apartment is left without natural light, which the architects accomplished by using glazed glass partitions with varying opacities and privacy curtains in lieu of standard walls. In our slideshow, tour the residence.