The proposed book is the first part of the work "Metal structures". The book describes the history of the development of metal structures and the main tasks of the science of metal structures. Data on steel and aluminum profiles are given, the work of steel and aluminum alloys under load is considered. The main provisions of the calculation of elements of metal structures on the basis of the method of limiting states. are given. The annex provides reference materials on the calculation and design of steel structures. The book is designed for engineering and technical workers of project organizations and students.