We were in York and didn't even go to this site. Duh. Is the bridge still there? The site marked? Must be marked. Harald did his best.
The town of Stamfordbridge has grown around the site - there's just a small monument there now.
http://tourguide.panoptics.co.uk/view.php?tid=26&fullscreen=true&PHPSESSID=9a924bb6d1294814964754c5d52276dc