Humans have used mirrors since as early as 600 BCE, employing highly polished obsidian as a basic reflective surface. Over time, people began to use small pieces of gold, silver, and aluminum in a similar manner, both for their reflective properties and for decoration. By the 1st century CE, people had started using glass to make mirrors, but it was only during the European Renaissance that Venetian manufacturers began making mirrors by applying metallic backings to glass sheets, remaining the most common general method of mirror manufacturing today. Since then, mirrors have continued to play both a decorative and functional role in architecture, serving a clean, modern aesthetic despite its ancient origins. Below, we investigate how mirrors are made, provide a brief history of mirrors in architecture, and offer several tips for architects looking to use mirrors in their designs.