The shelter of the early people changed dramatically from the paleolithic to the neolithic era. In the paleolithic, people did not normally live in permanent constructions. In the neolithic, mud brick houses started appearing that were coated with plaster. The growth of agriculture made permanent houses possible. Doorways were made on the roof, with ladders positioned both on the inside and outside of the houses. The roof was supported by beams from the inside. The rough ground was covered by platforms, mats, and skins on which residents slept. Stilt-houses settlements were common in the Alpine and Pianura Padana (Terramare) region. Remains have been found at the Ljubljana Marshes in Slovenia and at the Mondsee and Attersee lakes in Upper Austria, for example.