Strabo notes that "insulae", like "domus", had running water and sanitation, but this type of housing was sometimes constructed at minimal expense for speculative purposes, resulting in "insulae" of poor construction. They were built in timber, mud brick, and later Roman concrete, and were prone to fire and collapse, as described by Juvenal, the Roman satirist. Among his many business interests, Marcus Licinius Crassus speculated in real estate and owned numerous "insulae" in the city. When one collapsed from poor construction, Cicero purportedly stated that he was happy that he could charge higher rents for a new building than the collapsed one.