The Royal Gold Medal for a lifetime's work will be presented to architect Álvaro Siza later this week. The award which will be bestowed on Thursday 26 February will be presented by Her Royal Highness, Queen Elizabeth at a private ceremony at Buckingham Palace followed by a black tie event held by RIBA.

Adjudicated by jury chaired by RIBA President Sunand Prasad and comprised of architects Sir Jeremy Dixon of Dixon Jones, Prof Kenneth Frampton of Columbia University, Despina Katsikakis of design consultancy DEGW, Pankaj Patel of Patel Taylor, writer Sir Peter Davey OBE and engineer Jane Wernick Hon FRIBA, the decision was also officially approved by Her Royal Highness.

The official citation for the award reads: “Álvaro Siza is simply a profoundly complete architect who defies categorisation. The forging of a masterful and seemingly inevitable architecture out of the possibilities of a site is one of the supreme characteristics of Álvaro Siza’s architecture. He manipulates his readings of place into sculptural forms that are never predictable or ordinary, yet are never allowed to dominate over use or typological intelligibility.

"In Siza’s buildings, perhaps like no others, it is the relationships between the elements of the architecture that is given primacy rather than the shape or texture of the elements themselves. This is an architecture in which an economy of expressive means is combined with an abundance of spatial revelation.

"Álvaro Siza is, and always has been, a committed teacher and educator. He has enabled many younger architects to gain commissions through the work he was initially offered and this selflessness is one of many examples of his commitment to the greater architectural project, rather than to personal success.

"Unusually for an architect of such international standing, Siza has deliberately kept his studio small to ensure his attention to every project. He is generous with his appreciation of other architects.

"For the inspiring and instructive body of work he has produced over 40 years, and for his immense contribution to architecture through dialogue and teaching, the RIBA, on behalf of H. M. the Queen, is honoured to present the 2009 Royal Gold Medal for Architecture to Álvaro Joaquim Melo Siza Vieira. We wish him many more years of fulfilment of his unique vision of the possibilities of building.”