Architect: Zohar Architects
Location: Sofia, Bulgaria

Walltopia, a global leader in the design and manufacturing of artificial Climbing walls and grips, organized the Collider Activity Center competition located in Sofia, near the foothills of Mount Vitosha one of Bulgaria’s most popular tourist destinations. The proposal by Zohar Architects is a 100% climbable structure: a donut-shaped courtyard building informed by the diversity of context. Its volume is extruded using ‘grafts’ of the world’s most
famous mountains as formwork to create a patchwork of alpine geo-diversity, with a perfect cast of Abraham Lincoln’s nose from Mount Rushmore prominently positioned to satisfy curious climber fantasies. More images and architect’s descriptions after the break.

The programmatic mix combines exercise (climbing walls, fitness center, swimming pool, dance, and sports halls) with leisure (spa center, bar, restaurant, and café), and includes a park area with a greenhouse and other outdoor recreational spaces. Covered in a modular and easily transformable “Grip Grid’ façade that features climbable Walltopia plexiglass, the grip color, texture, and topography combine to create a product catalog building skin.

The 360° view walkway which caps the building offers an incentive for devoted climbers, with the interior program, following a similarly rewarding progression from active to passive. Two scalable entrances mark the transition into the building-a chimney and a cave with the former continuing into the ground to become the second-highest climbing wall in the world.

The Wallcano’s central courtyard is an actual 450m graft of land that is cut from Cherni Vrah-Vitosha’s highest peak to become the heart of the building. The piece removed is replaced with the mushroom boulder park (a required program that is now proposed off-site) that extends Walltopia’s presence to a tourist hotspot echoing a mountain’s change from hiking trail to the ski slope in order to accommodate the seasonal shift, the Wallcano, and connected park program similarly transforms twice a year. Rather than hibernating programs during the colder months, their use is extended through a proposed alternation of summer and winter functionality.

During the winter, the flexible grid-grip façade can be changed to incorporate Walltopia dry ice volumes for the ice-pick climbing. The pool transforms into a skate park, the beach volleyball court into an ice rink, and other programs adapt to the weather and facilitate a diversity of climbing experiences.

A rooftop sauna exhausts geothermally- generated steam through vents in the ceiling as the building joins the Iztok power plant chimneys to become a sustainable addition to Sofia’s existing artificial mountain range.