[igraph] How to Get Datasets

[Lorenzo Isella]

Dear All,
I hope this is not too off-topic.
I would like to try to analyze (pretty basic stuff to start from) some
real networks.
I thought about the tube stations of London underground, or the train
network of some area in Europe and so on, but then I bumped into the
problem of finding this data online already in a way suitable to be
loaded into an igraph graph object.
Is anything along the previous lines publicly available? I would like
to try my hands at something which is not a textbook example, is
within a desktop computing power, but allows me to explore a bit
igraph analysis and plotting capabilities.
Any suggestion is welcome.
Many thanks

Lorenzo