Columbia University's Professor Ken Jackson (above) teaches a course called The History of the City of New York. To fully demonstrate the urban environment around his students, he decided to take them o0ut on walking tours, but during daytime, there were always too many people on the streets. So now Jackson takes his youngsters out on bikes, starting at 11pm... riding through the city at night, he stops here and there to speak through a megaphone about various important sites and points. Rides typically last until 6am! So if you're woken up late at night by a voice entoning a history lesson, it may well be Jackson.