Complex sentence: The center of Kaminaljuyu is located a short distance from the oldest part of Guatemala City, and in the late 20th century the city grew around the ruins, and, in some places, over some of the outlying ruins before they were protected.
Split into simpler sentences: The center of Kaminaljuyu was located a short distance from the oldest part of Guatemala City. However, in the late 20th century, the city grew around the ruins, and, in some cases, over some of the outlying ruins before they were protected.