<p>Running Challenges by Keri Wallace showcases 100 of the best runs across Great Britain, from inspiring 5Ks through to epic multi-day ultras. Split into three sections ? England, Scotland and Wales ? and featuring a mixture of marked trails, organised races and unmarked self-navigated challenges, the runs ramp up in difficulty as you go through each section, so, whether you are a beginner or a more experienced trail, fell, mountain or ultra run...