The purpose of this book is to compare concrete casted on site to precast concrete elements in terms of price, time and quality of the finished structure. The objective was to examine the gains and losses of implementing either of the construction methods and find out under which circumstances it is economically feasible to employ either of the building systems. First of all the book will introduce what concrete and precast concrete is. The main focus in the book will be on demonstrating the main parameters that affect the cost of concrete structures as well as the time it takes to make them. The book sums up the biggest factors a designer must keep in mind when designing a construction that implements either concrete cast in-situ or precast concrete elements, in order to make an economically practical building. Finally, the book will make a case study where it compares the cost of constructing the same building using both building methods as well as the time it takes to construct it.