SLETH is a Danish office for architecture and planning. Our work bridges the gap between progressive urban vision and consistent quality in design realization. We work with internationally recognized buildings, urban plans, landscape projects and transformation of cultural heritage.



SLETH has gained more than 10 years of experience in dealing with complex planning cases, since winning the open international competition for the masterplan of the North Harbour, Copenhagen. We act as advisors, architects and planners for private and municipal clients – both national and international – to secure sustainable and liveable urban environments for cities to grow in. We work holistically with the urban scale, offering consultancy on local-, municipal-, master-, and development planning as well as design and detailing of specific urban spaces and elements.

Sustainable urban planning


The North Harbour was the first new Danish city district to be pre-certified with DGNB Platinum. The project embodies our approach to urban planning. Through intense analysis we identify the special nature of a given context; its predisposed potentials, its aesthetic qualities and its cultural heritage. We compose progressive visions for the future, facilitate collaboration and dialogue within complex client- and user constellations, and ensure value and quality in the final realization.

Cultural Heritage


SLETH is formed by a special appreciation of the Modernist movement in architecture and planning. In 2005 partners Søren Leth and Rasmus Therkildsen initiated and curated an exhibition about the Danish modernist Knud Blach Petersen, best known for his design of the large scale housing project Gellerup Parken in Aarhus. Through the exhibition Petersen, who at the time was widely discredited for his work, regained public interest in his practice, which has later led to several of his projects being listed as cultural heritage.

SLETH continues to work as advisors and architects for municipal and private clients on preserving and transforming Danish modernist masterpieces; among others the Danish School of Journalism (Kjær & Richter) and Herning Højskole (Viggo Møller-Jensen and Tyge Arnfred).


SLETH works integrated with landscape architecture in our design practice on both city- and building-scale. Driven by our ambition to create projects that are born from the existing conditions of the site, each project is tailored to weave together city, building, and nature to ensure synergies between the built and the grown. We work with a broad range of landscape disciplines including coastal resiliency, landscape analyses, placemaking, rainwater management, ressource mapping, planting strategies, beautification, and identity creation in our pursuit to make pleasant, robust, and futureproofing projects.

Besides insisting on reclaiming the role of nature in every project, we also work with stand-alone landscape projects such as Blåvand City Center in Southern Denmark and with reconstruction, renovation, and renewal of modernistic cultural landscapes such as Herning Højskole (C.TH. Sørensen) and The Aarhus School of Journalism (Sven Hansen).



SLETH has designed a range of widely acknowledged buildings, including Sonnesgade 11 and Tønder Townhall. We have a team of talented architects and constructing architects securing high quality in all phases of building – from initial sketching and programming, communicating with authorities, to final detailing and construction management.

We develop smart solutions in close collaboration with engineers and contractors to push the limits of sustainable architecture. We design for the future, considering everything from the lifetime of building materials across optimization of the construction process to the everyday use of the finished building. Our work balances the specificity of site and context with the versatility of programme, producing architecture that is anchored in its surroundings while being prepared for the future.



An integral part of the office’s DNA is cultural and communal engagement. SLETH regularly organizes exhibitions, lectures, workshops, and events for the general public with the intent to educate, discuss, and learn about the urban situations and communities that are at the very core of our work.

We support cultural-, health-, and educational institutions by developing grant applications and preliminary sketch projects with the aim of raising the overall quality of the built environment and ensuring a sustainable framework for public activities. Projects include refurbishment and additions to the DGI House in Aarhus, transformation of the former School of Journalism into a museum and community hub, and a new stadium for Bakken Bears.



At SLETH we believe in forming and managing trusting and long-lasting relationships with our clients and collaborators. We consider our office as an open workshop space and frequently invite project groups to join us for meetings centered around interactive physical models.

Our office in Sonnesgade 11 reflects our approach and process. We work collaboratively, hang our ongoing work on the walls, and are constantly sharing knowledge and experience with each other. The office is a dynamic container of physical models, drawings and material samples, all of which are actively used in our design process.

The Office


SLETH was founded in 2009 by partners and architects Søren Leth and Rasmus Therkildsen. With roots in the industrial South Harbor of Aarhus, Denmark, SLETH has evolved into a transdisciplinary and diverse studio employing 42 talented people with a wide range of professional backgrounds in its Aarhus and Copenhagen offices.

In 2016 SLETH moved into our current Aarhus location, Sonnesgade 11. The building, which is both designed and owned by SLETH, embodies the office’s unique approach to architecture, sustainability, and urban design. Our Copenhagen office is located within COBE, a long time collaborator, in Pakhus 54 in the North Harbour.

The work of SLETH is widely internationally published, exhibited, and recognized. The office is a recipient of a grant from the Danish Arts Foundation (2013) and the largest Danish architecture prize, the Nykredit Motivational Prize (2016). In 2017 Sonnesgade 11 was nominated for the Mies van der Rohe award, and several projects were exhibited in the Danish Pavilion of the Venice Biennial 2016.

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Recent projects