History-making manuscripts. These national archives of Britain include more than 12 million books, 180 miles of shelving, and the deepest basement in London. But everything that matters for your visit is in a delightful room labeled "Sir John Ritblat Gallery: Treasures of the British Library" and an adjacent room containing the Magna Carta. In this hour-long tour, we'll concentrate on a handful of documents - literary and historical - that changed the course of history. Don't forget to download the handy PDF companion map. Sightseeing nitty gritty: Cost: Free (donations appreciated); admission charged for some temporary exhibits. Hours: Mon–Fri 9:30–18:00 (until 20:00 on Tue), Sat 9:30–17:00, Sun 11:00–17:00. Excerpted from Rick Steves' London 2010. Copyright 2009 Avalon Travel. Related travel information at www.ricksteves.com.