Washington on Foot (Smithsonian, $3.75) began life primarily as a guidebook for city planners visiting this city; prepared for and published by the local chapter of the American Institute of Planners, it proved to have so much general interest that the Smithsonian has now made it available to a wider readership. The book is built upon 25 walking tours of the city (including one each for Annapolic and Old Town Alexandria), with an appended section listing recommended restaurants or stating - as it does for Capitol Hill East, to take it does for Capitol Hill East, to take only one example - that none is recommended.

Within this simple framework, the book presents a wealth of information and attractive maps and line drawings of various points of interest. Washington on Foot is extremely well prepared. The Smithsonian edition has improved slightly on the original (including, for example, a Metro map), but there wasn't really much room for improvement.

Those whose penchant for walking takes them farther afield may want to bring along Walking: A Guide to Beautiful Walks and Trails in America, by Jean Calder (Morrow, $3.95). It is not so gloriously detailed as the Smithsonian's more specialized book - understandably, since, it includes walking tours in every part of the country, from Cape Cod to Hawaii (Alaska has four pages, the District of Columbia 11).But it should be helpful for visitors interested in seeing the most notable features of a given region.

Among the most notable features of Washington - though unnoticed by most tourists and some residents - is the world's most distinguished array of monuments to black Americans. These include: bridges named for Whitney Young, Frederick Douglass and Duke Ellington, among others; the Martin Luther King Jr. Memorial Library; a school officially and a park unofficially dedicated to Malcolm X. Along with notable black churches, business, associations, educational institutions and other points of interest, these monuments are discussed briefly and presented pictorially in A Picture Guide to Black America in Washington, D.C., by Dolphin G. Thompson (Brownson House, 1502 Massachusetts Ave. SE, Washington, D.C. 2003, $4.95). Directed primarily to students and clearly intended to promote pride and a sense of participation in our city's black heritage, it is a book from which white adults can also learn.