City Tours From Google Labs

Google Labs have published about multi-day (or single day if you are the fast walking type) walking tours of major cities given a starting address. For startes, there are a few cities and walks suggested;

• Union Square, San Francisco
• 34th Street and 5th, New York
• London, England
• Dame Street, Dublin, Ireland
  

Except Dublin, I have walked the other cities, more or same the suggested routes. Let Google find nearby points of interest for you or (new!) create your own tours from your own and others' "My Maps".

Try City Tours