Definition and Significance:
In biblical terms, "strong cities" refer to fortified urban centers that were strategically important for defense, governance, and trade. These cities were often surrounded by walls and equipped with gates, towers, and other fortifications to protect against enemy attacks. The concept of strong cities is prevalent throughout the Old Testament, highlighting their role in the military and political landscape of ancient Israel and its neighboring regions.

Biblical References:

1. Jericho: One of the earliest and most famous examples of a strong city is Jericho. Known for its formidable walls, Jericho was the first city conquered by the Israelites under Joshua's leadership. The miraculous fall of its walls is recorded in Joshua 6:20: "So the people shouted, and the trumpets were blown. As soon as the people heard the sound of the trumpet, the people shouted a great shout, and the wall fell down flat, so that the people went up into the city, every man straight before him, and they captured the city."

2. Jerusalem: Jerusalem is another prominent strong city, serving as the political and spiritual center of Israel. King David captured the city from the Jebusites and established it as the capital. Under Solomon, the city was further fortified and became the site of the First Temple. Psalm 48:12-13 reflects on its strength: "Walk around Zion, encircle her, count her towers, consider her ramparts, tour her citadels, that you may tell the next generation."

3. Samaria: The capital of the Northern Kingdom of Israel, Samaria was a strong city built by King Omri. It served as a significant political and military hub until its fall to the Assyrians. 1 Kings 16:24 notes its establishment: "He bought the hill of Samaria from Shemer for two talents of silver and built a city on the hill, calling it Samaria, after the name of Shemer, the owner of the hill."

4. Hazor: Known as the "head of all those kingdoms" (Joshua 11:10), Hazor was a major Canaanite city that played a crucial role in the region. It was fortified and served as a center of power before being conquered by Joshua.

5. Lachish: This city was one of the most important fortified cities in the Kingdom of Judah. It was a key defensive site against Assyrian invasions, as described in 2 Chronicles 32:9: "After this, Sennacherib king of Assyria, while still besieging Lachish with all his forces, sent his servants to Jerusalem with a message for Hezekiah king of Judah and for all the people of Judah who were in Jerusalem."

Role and Function:
Strong cities served multiple purposes in ancient Israel and the surrounding regions. They were centers of administration, commerce, and military operations. The fortifications provided security for inhabitants and a refuge during times of war. The presence of strong cities often indicated the strength and stability of a kingdom or nation.

Spiritual Symbolism:
In a spiritual context, strong cities can symbolize the protection and refuge found in God. Proverbs 18:10 states, "The name of the LORD is a strong tower; the righteous run to it and are safe." This metaphorical use underscores the belief in God's strength and protection for His people, akin to the security provided by fortified cities.

Historical Context:
The construction and maintenance of strong cities required significant resources and labor. They were often located on elevated terrain or near vital trade routes, enhancing their strategic value. The archaeological remains of these cities, such as walls, gates, and towers, provide insight into the engineering and architectural capabilities of ancient civilizations.

Conclusion:
Strong cities played a vital role in the biblical narrative, serving as centers of power, defense, and refuge. Their presence in Scripture underscores the importance of security and stability in the life of ancient Israel and offers spiritual lessons on the protection and strength found in God.