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Cave-Like Monolith Crafted from Black Sand and Glacial Water

Authors:
Pablo Castro, Louis Boulacheb
Cave-Like Monolith Crafted from Black Sand and Glacial Water
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Crafted from black sand and glacial water, the monolithic structure embodies a cave-like form that offers visitors an immersive experience while engaging with the surrounding Icelandic landscape.
5 key facts about this project
01
Crafted using 75% black sand, emphasizing sustainability and local materials.
02
Features a vertical cavity design that mimics natural cave formations.
03
Integrates rainwater collection for sustainable water management.
04
Includes an observation deck that provides 360-degree views of the landscape.
05
Facilitates unique sensory experiences through steam and heat within the cave-like structure.

The project sits in a valley, responding to the area’s natural features and elemental characteristics. It is designed as a monolithic structure that integrates with its surroundings, encouraging curiosity and exploration. The overall concept focuses on a vertical cavity that reflects the attributes of a cave, offering both immersive experiences and connections to the geological components of the site.

Design Concept

At the heart of the design is a form that takes inspiration from simple shapes present in the local environment. This choice enhances the relationship between the building and the landscape. The monolith allows for both enclosed spaces and wide views, creating a balance between privacy and openness that resonates with visitors.

Visitor Experience

The journey to the structure is carefully planned. Visitors start from a designated parking area and make their way to a small visitor center. From there, they ascend towards an observation deck, encountering viewpoints along the way that showcase the surrounding landscape. This thoughtful pathway deepens the connection between visitors and their environment, preparing them for the experiences within the cave-like space.

Material Composition

Construction comprises specific materials: 75% black sand, 15% cement, and 10% water sourced from Icelandic glaciers. This mixture underscores a commitment to sustainability and ensures low maintenance for the structure. Utilizing local materials strengthens the project's ties to the geology of the area, reflecting the natural landscape it inhabits.

Spatial Dynamics

Inside, the design emphasizes interactions with fundamental elements like water, steam, and rock. The spatial arrangement creates various sensory experiences that engage visitors. As they descend into the cave, they feel the heat, encounter steam, and experience the unique moisture present in this geological setting. This design choice invites individuals to connect more deeply with the architecture and landscape surrounding them.

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The Buildner’s Unbuilt Award 2025: Celebrating Architectural Creativity and Visionary Unbuilt Designs with a Total Prize Fund of €100,000

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Competition organisers

The Buildner’s Unbuilt Award 2025 is an international architecture competition dedicated to recognizing and celebrating the value of unrealized architectural designs. It invites architects, designers, and students worldwide to submit visionary projects that have not yet been constructed, highlighting the power of ideas and the creativity behind the design process. By focusing on unbuilt work, the competition aims to bring forward concepts that shape the future of architecture and push the boundaries of the profession. 

Participants can compete in three categories based on project scale: Small Wonders (up to 100 m²), Medium Marvels (101–999 m²), and Large Visions (over 1,000 m²). Each category winner will receive €20,000, and additional prizes include honorable mentions, student awards, and a special Best Presentation Award. Winning projects will gain significant international exposure through Buildner’s publicity campaign and a feature article on ArchDaily, providing a unique opportunity to showcase creative ideas to a global audience. 

The Buildner’s Unbuilt Award 2025 encourages entrants to submit any type of unbuilt project, from conceptual visions to detailed designs, celebrating bold innovation without the constraints of realization. Important deadlines: registration closes on October 30, 2025; submissions are due by November 20, 2025; winners will be announced on December 17, 2025.

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Celebrating your unbuilt architecture visions with a €100,000 prize

100,000€ Prize / 2025 ideas COMPETITION
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Final registration deadline 30 October 2025

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