The subway system is an indispensable part of every modern metropolis. Building a subway is no longer a matter of prestige but a necessity, a consequence of the traffic revolution worldwide. This paper shows four metro studies with specific reference to the Belgrade subway and problems that occurred. The first one was conducted in 1946 by the famous Serbian architect Nikola Dobrovic. This document is indeed the first written record discussing the subway issue in Belgrade. The next study dates back to 1968. This project was the first major study on the possibility of a subway. The third and biggest, this subway study was completed in 1982 and contained a major and comprehensive subway project. This project was officially accepted and enacted by the city government. The fourth project in circulation with regard to the subway is the light city railway project. It came out due to the consequences of the decision that a classical subway was not necessary in Belgrade, so that a replacement for the classical subway system was to be undertaken. The light city railway project was adopted as a part of the General Urban Plan for Belgrade by the year 2021.