Even awesome birthday celebrations won't derail the 30 Days meme! The next on the list is favorite era visited by the Doctor. As an English major, I am obligated to say Elizabethan England in "The Shakespeare Code" (okay, I'm not really obligated - I actually wanted to say that).
The Globe Theatre! THE GLOBE THEATRE! The fact that the production crew actually went to the Globe Theatre to film parts of this episode makes my heart squeal with glee. Not to mention the fact that this episode explored the mystery of Shakespeare's lost play "Love's Labour's Won" - and all the Shakespeare-title drops in the dialogue. Plus, Dean Lennox Kelley is an fabulous William Shakespeare (haters, kindly locate the closest exit. Most likely near your left).
(oh, and love the gratuitous references to "Harry Potter" - but this is supposed to be about the era this story is set in).
For a supposedly "low-budget" science fiction TV show (hee hee - air quotes), they did a wonderful job of depicting Shakespeare's time and setting the tone for the entire story and it's fairly accurate (as far as I can tell, at least). I even showed this to the kids in the English class I assistant-teach when we did our Shakespeare unit and they got a lot out of it, which is a testament to how important Shakespeare is and how much his work has permeated our modern culture. This is definitely my favorite historical "Doctor Who" episode.