Mercury's most well-known feature is the Caloris Basin. This huge crater-like feature on Mercury's surface resulted from an ancient encounter with an asteroid. It is quite large, measuring 800 to 950 miles in diameter. Because of its size, it is termed a basin rather than a crater.
According to NASA, the Caloris Basin "is one of the solar system's largest impact basins." Considering Mercury's diameter is just over 3,000 miles, the Caloris Basin is a prominent feature of the planet. Pictures from space even show smaller craters within the Caloris Basin. Like much of the rest of the planet, the basin appears wrinkled.