Vacationing in London this summer? Save with a sightseeing pass.

These shave the high price of visiting castles, gardens, and historic houses. Some, including the Great British Heritage Pass and the English Heritage’s Overseas Visitor Pass, are for specific lengths of time, from four days to a month. The National Trust’s pass must be purchased before your trip. If you’ll be spending time in Scotland, look into the Historic Scotland’s Scottish Explorer Ticket or the National Trust for Scotland’s Discovery Ticket. The VisitBritain Web site (www.visitbritain.us) has information about these and other discounts; match what the pass or membership offers against your itinerary to see whether you’ll save money. See our London coverage.