Milestones in your life are those significant events that mark the path of your life.
They are flags or signs that identify who you are. Families, churches, organizations, communities, tribes, and nations also have milestones. They mark, signal, or identify. They tell you about your heritage.
The final milestone is death. We visit gravesites and usually there is a marker there and we see the ending place of a life and look backwards. A memorial of stones was made after the Israelites crossed the Jordan into the land of promise:
So Joshua called together the twelve men he had appointed from the Israelites, one from each tribe, and said to them, "Go over before the ark of the LORD your God into the middle of the Jordan. Each of you is to take up a stone on his shoulder, according to the number of the tribes of the Israelites, to serve as a sign among you. In the future, when your children ask you, 'What do these stones mean?' tell them that the flow of the Jordan was cut off before the ark of the covenant of the LORD. When it crossed the Jordan, the waters of the Jordan were cut off. These stones are to be a memorial to the people of Israel forever."