Final answer:
The pyramids built by Pharaoh Sneferu in the 4th dynasty around 2600 BCE were the Bent Pyramid and the Red Pyramid.
Step-by-step explanation:
In the 4th dynasty around 2600 BCE, the Pharaoh Sneferu built two pyramids: the Bent Pyramid and the Red Pyramid. The Bent Pyramid, also known as the Sneferu's Pyramid, is called so because of its unique shape, with a change in angle halfway up. The Red Pyramid, named after the reddish limestone on its surface, is the third-largest pyramid in Egypt and is considered to be the world's first successful smooth-sided pyramid. It is important to note that the pyramids of Khufu, Khafre, and Menkaure were built by different pharaohs during the 4th dynasty, but not by Pharaoh Sneferu.