February 27, 2012.  The summer Olympic games take place in London from July 27 through August 12, 2012.  Even if you don't get tickets to specific events, Hyde Park and other places will have large screen outdoor televisions set up to view the games.

How to get Regular Tickets to the London Olympic Games:

The official site to get tickets is http://www.tickets.london2012.com/ Currently, no tickets are available:

Ticket sales information: The countdown is on to the London 2012 Games.
As part of our preparations, we are currently allocating seats to ticket holders. During this time ticket sales will be closed. Further details about future ticket sales will be available on this website from spring 2012.

If you are a resident of the UK or a designated European country, you are eligible to purchase tickets for the London 2012 Olympic Games and Paralympic Games on this website.

If you are a resident of a designated European country you can purchase tickets through your local National Olympic Committee (NOC) or their appointed Authorised Ticket Reseller (ATR) or your local National Paralympic Committee (NPC) or their appointed Authorised Ticket Reseller (ATR).

If you are not a resident of the UK or a designated European country, regardless of citizenship, you will need to purchase tickets for the London 2012 Olympic Games and Paralympic Games through your local National Olympic Committee (NOC) or their appointed Authorised Ticket Reseller (ATR) or your local National Paralympic Committee (NPC) or their appointed Authorised Ticket Reseller (ATR)