Arcology, a portmanteau of "architecture" and "ecology", is a field of creating architectural design principles for very densely populated and ecologically low-impact human habitats.

The term was coined in 1969 by architect Paolo Soleri, who believed that a completed arcology would provide space for a variety of residential, commercial, and agricultural facilities while minimizing individual human environmental impact. These structures have been largely hypothetical, as no arcology, even one envisioned by Soleri himself, has yet been built.

The concept has been popularized by various science fiction writers. Larry Niven and Jerry Pournelle provided a detailed description of an arcology in their 1981 novel Oath of Fealty. William Gibson mainstreamed the term in his seminal 1984 cyberpunk novel Neuromancer, where each corporation has its own self-contained city known as arcologies. More recently, authors such as Peter Hamilton in Neutronium Alchemist and Paolo Bacigalupi in The Water Knife explicitly used arcologies as part of their scenarios. They are often portrayed as self-contained or economically self-sufficient.