Christopher Swingley wrote:

>
> Every time I go back there, I'm amazed that I was able to do all that,
> by myself, with nothing but a couple winches, a pulley, some ropes and
> a simple A-frame.  Physics is pretty cool.

There was an excellent program on UK TV concerning
the erection (not casting) of Abraham Darby's Iron Bridge.

Short version - A frames and rope.

Long version:

http://www.hdowns.co.uk/ironbr
idge4.htm

(hell, it was back in 2001)

  BugBear