Broughton Wall at the Fit City Leisure Centre in Broughton, Salford is considered by many to provide the best indoor bouldering in the UK and is home to about 2000 problems of all grades. Access had suffered from council cutbacks but I would just like to bring to your attention that it has recently improved again thanks to the efforts of Dave Hinton.
It is now open until 21-30 every Tuesday evening and a good Tuesday scene is starting to develop. On other weekdays it is currently only open until 19-00 although if the Tuesday evening sessions are successful this may improve. It is also open at weekends but then it is best to call and check before going as opening may not be so reliable.
I have been on the last three Tuesdays and these visits have reminded me that it provides by far the best training for outdoor climbing (particularly on limestone) of any bouldering wall I have ever encountered. It is also an extremely enjoyable place to spend an evening with a very different style of problem that is complementary to what is provided by the mainstream bolt on walls. It has no bolt ons on the main wall so the problems never change and your favourite benchmark problems never disappear. Nevertheless there are so many recorded problems in each grade that there is always something new to try.
There is always a copy of the guide to the 2000+ existing problems (and currently a sheet of comp problems) in the bouldering room to show you what to go at if you don't want to make up your own.
If you have used Broughton before, go back and get re-acquainted. If not, get down there and see what you have been missing!