The "B.C. Era," or "Before Christ Era," refers to the time period before the birth of Jesus Christ. It is commonly used in the Gregorian calendar, which counts years backward from the year 1 A.D. (Anno Domini). The B.C. Era includes significant historical events, cultures, and civilizations, such as the rise and fall of the Roman Empire, the development of Ancient Egypt, and the establishment of Mesopotamian societies. In this era, various advancements were made in areas like agriculture, writing, and architecture. Notable achievements include the construction of the Great Pyramids of Giza and the invention of cuneiform writing in Sumer. The B.C. Era laid the foundation for many aspects of modern civilization and continues to be studied by historians and archaeologists.