If you could only one book that you could recomend to anyone, what would it be.

It's hard to recommend without knowing what the person was interested in, but my all time favorite book is The Time Travellers Wife - not historical fiction.  If it's HF you're looking for I'd say Gone With the Wind or Roots.  See I couldn't limit it to just one. 

Summer of the Monkeys is my absolute favorite book.  So of course I would recommend that to anyone.

The Historian by Elizabeth Kostova. I recommend that all the time. It has mystery, fantasy, and history all rolled in one.

I would probably recommend an American classic - and what leaps most readily to mind is Little Women, Louisa May Alcott, one of America's literary gems. As a story of American family, of American spirit set against the horrors of our civil war, I think everyone should read this book at least once.

Kelly

For a classic, I'd recommend The Good Earth by Pearl Buck.  It takes place in early twentieth century China but the emotions and struggles it conveys are timeless.  A very moving story.

For something a bit newer, Margaret George's Memoirs of Cleopatra.  Although daunting because of its size, you really feel as if you are in Egypt with Cleopatra - I got lost in this book.  This one got me hooked on the HF genre.

I only just discovered historical fiction and what won me over was Rosemary Sutcliff's The Mark of the Horselord.

The Sunne in Splendour by Sharon Kay Penman. Loved it! I also really loved Lonesome Dove by Larry McMurtry.

I think along the same lines as Kelly---if I didn't know the reader, then one of my favorite classics, To Kill a Mockingbird.  If I knew I was dealing with 'one of us', then if that person was an HF relative newbie, probably a Diana Gabaldon. If hardcore, then it would really depend on his/her fave period, what he/she'd already read...could be anything. Maybe An Instance of the Fingerpost , Fingersmith or even The Painted Veil.

I'd recommend Pride and Prejudice by Jane Austen as my all time favorite.

Animal Dreams by Barbara Kingsolver.

But, like others have said, it also depends on what I know the person likes and enjoys reading.