OOA is an Accra-based architectural practice founded in 2006 by Martin and Rosemary Orthner, Austria-trained architects with a distinctive vision. Blending global expertise with local insight, we deliver innovative design solutions rooted in both international standards and Ghana’s unique socio-cultural and environmental context.  

We have established strategic partnerships with leading international firms, including HOK, ZGF, ARUP, and PBP+W and have worked with clients such as the World Bank/IFC, Oracle, Google, IMF, and the EU. Our portfolio includes some of Accra’s most iconic and forward-thinking architectural projects.  

Renowned for our structured methodology and precision, we are a trusted partner for complex, cross-border collaborations.  

We cultivate a collaborative environment that thrives on two-way dialogue, ensuring seamless integration of global expertise and local innovation.

Every project prioritizes resource efficiency—from low-energy systems and passive climate strategies to solar integration and water treatment—aligning sustainability with timeless design.  

We bridge Ghana’s rich social and environmental fabric with world-class architectural execution, creating spaces that are culturally resonant, environmentally responsible, and economically viable.