interresting places in Washington

read this extract from a page of the Washington Tourism Office website and answer the following questions.

"The National Mall, home to many of the magnificent museums of the Smithsonian Institution, is a great place to start your day. See the magnificent jewels, dinosaurs and mammals on display at the National Museum of Natural History, the airplanes and interactive flight simulators at the National Air and Space Museum, and the stories, arts and crafts at the National Museum of the American Indian. And it's all free of charge. The museums also offer free tours to groups who reserve in advance. There's more to explore on the National Mall than just the Smithsonian Institution. Art lovers won't want to miss a visit to the National Gallery of Art, while the National Archives is a must for any American history buff."

Questions :

1- What are the different museums near the National Mall?

2- How much would a tour cost for my group ?