The recent discovery of giant DNA viruses and the understanding that such viruses are diverse and abundant blurred the difference between viruses and cells. Our laboratory studies two representatives viruses of the Megavirales order: the PBCV-1 and the Mimivirus with its famous stargate. The exclusive cytoplasmic replication cycle of Mimivirus, as well as generation of viral factories of PBCV-1 have been studied extensively in our laboratory using advanced microscopic methods such as electron microscopy and high-resolutionlight microscopy, along with the use of molecular approaches. Some of our open questions focus on the viral assembly, infection cycle, and the generation and composition of the complex and dynamic structures of the viral factories, that some claim may be the origin of the nucleus in eukaryotes.