Mark ye well her bulwarks - Margin, as in Hebrew, "Set your heart to her bulwarks." That is, Pay close attention to them; make the investigation with care, not as one does whose heart is not in the thing, and who does it negligently. The word rendered "bulwarks" - חיל chêyl - means, properly, a host or army, and then a fortification or entrenchment, especially the "ditch" or "trench," with the low wall or breastwork which surrounds it: 2-Samuel 20:15; Isaiah 26:1. (Gesenius, Lexicon) The Septuagint translates it here: δύναμις dunamis, power; the Vulgate, "virtus," courage; Luther, "Mauern" - walls.
Consider her palaces - The word "palaces" here refers to the royal residences; and, as these were usually fortified and guarded, the expression here is equivalent to this: "Consider the "strength" of the city; its power to defend itself; its safety from the danger of being taken." The word rendered "consider" - פסגוּ pasegû - is rendered in the margin "raise up." The word occurs nowhere else in the Bible. According to Gesenius (Lexicon), it means to "divide up;" that is, to walk through and survey them; or, to consider them accurately, or in detail, one by one. The Vulgate renders it "distribute;" the Septuagint, "take a distinct view of (Thompson);" Luther, "lift up." The idea is, "examine attentively" or "carefully."
That ye may tell it to the generation following - That you may be able to give a correct account of it to the next age. The "object" of this is to inspire the next generation with a belief that God is the protector of the city; that it is so strong that it cannot be vanquished; that there is safety in such a city as that. As applied to the church now, or at any time, it means that we are to take such views of its being a true church of God; of its being fixed on firm foundations; of its being so able to resist all the assaults of Satan, and of its being so directly under the divine protection, that it has nothing to fear. It will and must stand to all coming time, a place of absolute safety to all who seek protection and safety within it. The following remarks of Dr. Thomson (Land and the Book, vol. ii., 474, 475), may furnish an illustration of what the ancient defenses in the city may have been, and especially of the word "towers" in this passage in the Psalm: "The only castle of any particular importance is that at the Jaffa Gate, commonly called the Tower of David. The lower part of it is built of huge stones, roughly cut, and with a deep "bevel" round the edges.
They are undoubtedly ancient, but the interspersed patch-work proves that they are not in their original positions. I have been within it, and carefully explored all parts of it that are now accessible, but found nothing which could cast any light upon its history. It is believed by many to be the Hippicus of Josephus, and to this idea it owes its chief importance, for the historian makes that the point of departure in laying down the line of the ancient walls of Jerusalem. Volumes have been written in our day for and against the correctness of this identification, and the contest is still undecided; but, interesting as may be the result, we may safely leave it with those who are now conducting the controversy, and turn to matters more in unison with our particular inquiries. Everything that can be said about this grand old tower will be found in the voluminous works of Williams, Robinson, Schultz, Wilson, Fergusson, and other able writers on the topography of the Holy City."

Mark ye well her bulwarks - See the redoubts by which she is defended.
Consider her palaces - See her courts, chambers, altars, etc., etc.; make an exact register of the whole, that ye may have to tell to your children how Jerusalem was built in troublesome times; how God restored you; and how he put it into the hearts of the heathen to assist to build, beautify, and adorn the temple of our God.

Mark ye well her bulwarks,.... Such as the free favour of God in Christ; which is not only as a shield, but as a bulwark to the church; his everlasting love, electing grace, the covenant of grace, with its blessings and promises, all which are more immovable than rocks and mountains; and especially the power of God, which surrounds his church, as the mountains did Jerusalem; and by which they are kept and preserved as in a garrison, Psalm 125:2. Also salvation by Christ; his righteousness, sacrifice, and satisfaction, which God has appointed for walls and bulwarks, and which make the city, the church, a strong and impregnable one, Isaiah 26:1. Likewise the Spirit of God, and his operations and influences, which are a standard against the enemy's flood of opposition and persecution; and who being in his church and people, is greater than he that is in the world, Isaiah 59:19, 1-John 4:4. Some render the words, set "your hearts on her strength", as the Vulgate Latin version; that is, on Christ, who is the strength of the poor and needy in their distress; the strength of their hearts, of their lives, and of their salvation, and the security of the church. Others readier them, "set your hearts on her armies"; as the Targum is; her volunteers, her soldiers, who endure hardness as good soldiers of Christ, fight the Lord's battles, and are more than conquerors through him; and a lovely sight it is to behold them, with Christ at the head of them; see Revelation 19:14;
consider her palaces; for Jehovah, Father, Son, and Spirit, have their dwelling places in Zion; and here, besides apostles, prophets, evangelists, and ordinary ministers of the word, who are rulers and officers set in the first place, every saint is a prince and a king; and has a place and a name here, better than that of sons and daughters of the greatest potentate on earth; every dwelling place in Mount Zion is a palace.
that ye may tell it to the generation following: that is, the beauty and glory, strength and safety of the church; and even all that is spoken of her in this psalm, as well as what follows: this is the end proposed by taking a circuit round Zion, and making the above observations on it.

Tell it - That they may continue their praises to God for this mercy, by which they hold and enjoy all their blessings.