I live in Bradford and there could be a number of things the OP was referring to.
The Park in the Heart is a scheme currently under way to create a park around the City Hall area where the old police station and magistrates court now stand.
It could be you were referring to the Westfield shopping centre planned for the city centre. Demolition around the site began in 2004 but the original developer collapsed. Westfield took on the project but have been heel dragging due to lack of tenant interest, economic climate and their need to focus on prioritising the London Olympic Village shopping centre first. This fiasco has left a huge muddy field in the centre of the city with no sign of progress for ages. There has been local pressure to turn the area into a park (or do something with it) for quite some time. See here.
The other thing you might be referring to is the now abandoned idea of moving Bradford City football team and the Bradford Bulls to the Westfield site with the building of a new stadium.