EN
The paper discusses questions related to the determination of the lifespan and functionality of wood-soil fortifications of early medieval hillforts. The paper builds on our experiences gained during nearly twenty years of observations at the archaeological open-air museum in Modrá near Velehrad in Moravia, Czech Republic. We compare our findings with other archaeological open-air museums and research concerning fortifications. The paper presents older as well as the most recent reconstructions of fortifications built in Modrá between the years 2020 and 2021. Those constructions are then compared with similar fortifications recently reconstructed on the Bojná-Valy hillfort near Topoľčany in Western Slovakia. Finally, we briefly discuss several questions concerning hillforts and their fortifications in the Great Moravian times (9th c.).