There is nothing like actually seeing a place, even 100 years later. It gives your writing credibility and confidence. For example, Send the Word’s chapters in Kingsland changed after I visited it (and could see the Statue of Liberty from the bluff overlooking the site of the explosion, a great detail for the book). I couldn’t have written So Beware without knowing Paris or Berlin. I hired a guide to walk me through the Meuse-Argonne for Send the Word.