Kings Cross was named after a monument for King George IV but the area was settled much, much earlier. St Pancras old church originated in 4BC. These days it's most famous for its train station: Kings Cross/St Pancras. From here trains go all over England, including to Hogwarts if you can find Harry Potter's Platform 9 3/4. It's also home to Eurostar, which whisks you to Paris and Brussels.
The surrounding area is slowly edging its way out of being one of the seediest parts of London. The magnificent St Pancras building is coming back to life as a posh hotel, the British Library is just down the road, and of course, the station redevelopment is full of shops and restaurants.