Perhaps the best classic introduction to abstract algebra at undergraduate level ,introducing :numbers ,groups ,polinomials ,linear structures ,commutative rings ,transfinite aritmetic ,algebraic and transcendental extensios of fields and galois theory.
Both Birhoff and Mclane were important mathematicians,Mclane for example was one of the builders of the homological algebra and the categories theory
This classic book is to be treasured ! I believe B & L wrote this book with the objective to welcome newcomers into the wonderful world of Abstract Algebra !