The bookmaker has placed the Evelina Children's Hospital in London and Richard Rogers' New Terminal at the Barajas airport in Madrid as joint second-favourites.
The rank outsiders are Adjaye Associates' Idea Store and the Phaeno Science Centre in Germany by Zaha Hadid.
The full odds are:
Brick House - 9/4
Evelina Children's Hospital, London - 7/2
Idea Store, Whitechapel, London - 6/1
National Assembly for Wales, Cardiff - 3/1
New Area Terminal, Barajas Airport, Madrid, Spain - 7/2
Phaeno Science Centre, Wolfsburg, Germany - 6/1