The plan and structure of the private house has always been conditioned by certain factors as climate, local construction materials, economic potential, historic and social data. In Greece, climate was the determining factor that caused the formation of certain types of house like the megaron and the house with an atrium. The same factor must probably have been responsible for the fact that Greeks did not, in general, pay much attention to the aesthetic improvement of their houses. Having a mild, sunny weather, Greeks used to spend much of their time outdoors. Even when public architecture was in its heyday (5th century BC) the private house remained insignificant. Two main types of house plan were in use as early as 3.000 BC, the curved and the rectangular, the latter being the most popular. The megaron and versions of the megaron were among the most important of the rectangular type of building, but also the most popular since they remain in use from prehistoric times down to our days. In mainland Greece, however, besides the rectangular,the curved type of building was also in use, which started developing from the archaic period to the byzantine age and even later. The prytaneia, the tholoi and the hellenistic royal monuments testify to the popularity of this type of public architecture.