I subscribe to 'Lost Cousins' which gives a monthly newsletter that contains some good links.
This month was a link to MAPCO which is a free site with high definition historic maps especially of London although it mentions UK and Australia. A quick browse showed an illustration of Gallipoli
example urls - Lost Cousins
http://lostcousins.com/newsletters/mar11news.htm
mapco
http://mapco.net/london.htm
Found my father's birthplace (now covered by St Thomas's Hospital) within a couple of minutes
Hope this is useful to someone
Chris
ID:5026