I'll be visiting London soon and I'll have only one day (a Sunday) to see major tourist attractions. Are most attractions and businesses open on Sundays?
Most attractions are open on Sundays, but a number are just open for 6 hours, from 11:00-17:00 or 12:00-18:00, so be sure to check each one individually. A TripAdvisor discussion about this topic.
If you want to enter specific attractions, be sure to visit their websites for business hours. (Google maps will include hours). I love using google to map out my destinations. Save the outdoor attractions for before and after business hours to maximize viewing time.
You can view the London Eye, the Big Ben, Westminster Abbey, the bridges (London bridge, Millennium, Tower, etc), Shakespeare's Globe within walk distance and before and after regular business hours. All these attractions are around the Thames river. These can be very lovely lit up at night. The Millennium bridge is lit up at night and leads you towards St Paul's in the distance (from the South of the Thames).
Assuming some of these are on your list, you can see how to plan your route if you're walking. You can see signs for the underground in between all areas. Leicester square was included if you like Broadway, Lego, or Nickelodeon. Piccadilly for shopping (I love Fortnum & Mason!).
A wide variety of theater, galleries, and museums are scattered between all locations. You'll have to narrow down the specifics (photography, musicals, modern galleries, history, etc).