www.si.edu/.NATIONAL MALL: The nearly two-mile grassy expanse between the Capitol and Potomac River features memorials honoring five presidents (including Washington, Jefferson and Lincoln) as well as Martin Luther King Jr. and battle monuments in tribute to America's veterans. One of the best times to visit is in the evening, as the monuments are lit and crowds have dwindled.Beyond the large monuments, there are dozens of smaller statues, historic sites and walking paths along the Mall. The National Park Service offers a free new mobile app with a map and details on the sites: www.nps.gov/nama/photosmultimedia/app-page.htm. The park also draws about 1 million people each year to see its famous cherry blossom trees when they reach full bloom in late March or early April. Some of the oldest trees that were a gift from Japan line the Tidal Basin and make a picturesque view.BEHIND THE SCENES: Washington is a city where everyone wants special access and a look behind the scenes of power. One of the best ways is to plan ahead. Call your member of Congress to request a personal tour led by a congressional staffer. Visitors can also ask for a tour of the Capitol dome. White House tours are also normally available through congressional offices, though they have been halted temporarily due to government budget cuts. International visitors can request tickets through their country's embassy.If you don't have time for reservations, the Capitol Visitor Center offers free exhibits and tours of the Capitol. Tickets are available online. A limited number of same-day passes also are distributed at the information desks each day. The center also offers specialty tours on the Capitol's history and artwork.The Library of Congress offers free access and impressive architecture near the Capitol. Volunteers offer free, guided tours of the nation's oldest cultural institution. www.loc.gov/visit/tours/.PRESIDENTIAL SITES: A walk through downtown Washington offers a chance to connect with presidential history. A short walk from the White House, Ford's Theatre, where President Abraham Lincoln was assassinated, offers daily tours with free same-day tickets distributed each morning at 8:30 a.m. Otherwise, advance tickets are $2.50 per person.A five-minute walk from the theater, visitors will find the National Portrait Gallery. Its most popular collection is the presidential portraits, including some of the most famous images of George Washington and Abe Lincoln.WATERFRONT AND KENNEDY CENTER: Washington is increasingly embracing its once-neglected waterfronts. New gardens and walking paths are bringing new life to these spaces. In Georgetown, a new park along the Potomac River has become a popular place to relax. Take a stroll along the water. Bring a picnic or stop for a late lunch at a riverside cafe. Then head toward the Kennedy Center along the river. This living memorial to President John F. Kennedy offers free tours with no reservations required. Arrive in time for the 4:30 p.m. tour of the theaters and concert halls. Then stay for a free Millennium Stage performance every day at 6 p.m. The dress code for free shows is casual. The evening views from the Kennedy Center's rooftop are a treat.