This book is the result of lecture courses on algebraic topology given by the author at the University of Manchester in 1967-1970, at Cornell University in 1970-1971 and at the Georg August University, Gottingen, in 1971-1972. The level of the material is more advanced than that of a first-year graduate course in algebraic topology; it is assumed that the student has already had a course on basic algebraic topology which included singular homology, the fundamental group and covering spaces. Moreover, a student who has never encountered differentiable manifolds will probably have difficulty with Chapter 12. On the other hand nO knowledge of homotopy theory beyond the fundamental group is assumed.