Search london history from Roman times to modern day
A bit out of date, but this interactive map of step free London is very good
All the London railway stations :
London Overground (Watford DC Line) & Bakerloo,
AccessAble :
Accessibility friendly : Harlesden is not accessible to wheelchair users due to stairs between the platform and street level.
General description : See wiki
More comment : National Rail Map & Guide, 24 steps to platforms.