Directly south of the White House, the marble Jefferson Memorial stands in tribute to the nation's third president. Architect John Russell Pope modeled it after the Pantheon in Rome, which Thomas Jefferson admired. Dedicated in 1943, a hollow, bronze statue of the philosopher-president sits inside, surrounded by walls inscribed with some of his famous writings, including an excerpt from the Declaration of Independence. The Jefferson Memorial overlooks Washington's scenic man-made lake, the Tidal Basin, where paddle boats dot the placid water on warm days.

The Lincoln Memorial is a tribute to the president who fought to preserve the nation during the Civil War. Architect Henry Bacon modeled the 80-foot-high marble building on the Greek Parthenon. Artist Daniel Chester French sculpted the hands on the statue of Abraham Lincoln to spell out "A" and "L" in American sign language, as a reminder that Lincoln signed into existence the nation's only deaf college, Gallaudet College. Lincoln's stirring Gettysburg Address is inscribed on the south wall of the monument, and in 1963, Dr. Martin Luther King Jr. delivered his "I Have a Dream" speech from the steps of the memorial.

Congress authorized the Vietnam Veterans Memorial in 1980 as a tribute to those who served in one of America's least popular wars. More than 58,000 names -- of those who are missing or lost their lives -- are etched in the black granite panels, which reflect the surrounding trees, as well as the faces of visitors searching for loved ones' names. Maya Ying Lin, who designed the memorial, called it a "moving composition." But upon completion, critics decried the memorial as too stark. The addition of a Frederick Hart statue of three soldiers won many of them over.

On Veterans Day in 1993, the Vietnam Women's Memorial by sculptor Glenna Goodacre was dedicated in Constitution Gardens to represent the work of Vietnam's female veterans. The monument features three women: two in uniform caring for a wounded male soldier, and a third woman kneeling nearby.

The Smithsonian Institutionwhich originally housed all its collections in one building, has become the world's largest museum complex. More than 135 million objects can be found in its collections (only about one percent of them are on display). Almost a dozen museums -- including the National Air and Space Museum, the National Gallery of Art and the National Museum of American History -- ring the expanse of green known as the Mall. Entry to all the Smithsonian museums is free, as are most guided tours.