Whilst there are other questions I have found similar to this one, they do not specifically seem to explain the exact start date for the 70 week prophecy in Daniel regarding the command to rebuild Jerusalem.
If we read the Daniel 9:25 prophecy, verse 25 talks about "restore and rebuild Jerusalem".
Cyrus decrees in Ezra 1 to Return to Jerusalem and Build the Temple
In the first year of Cyrus king of Persia, to fulfill the word of the LORD spoken through Jeremiah, the LORD stirred the spirit of Cyrus king of Persia to send a proclamation throughout his kingdom and to put it in writing as follows:
2“This is what Cyrus king of Persia says:
‘The LORD, the God of heaven, who has given me all the kingdoms of the earth, has appointed me to build a house for Him at Jerusalem in Judah.
Zerubbabel is among those who return to carry out this decree.
Enemies of the tribes obtain a decree to stop construction
King Artaxerxes, in the first year of his reign, after being told by the "enemies of Judah and Ephraim" and also consulting the original decree given by Cyrus, believes the Israelites are in breach of said decree (in that only the Temple may be built) and stops the entire process.
Ezra 4 12 "Let it be known to the king that the Jews who came from you to us have returned to Jerusalem. And they are rebuilding that rebellious and wicked city, restoring its walls, and repairing its foundations." 21 Now, therefore, issue an order for these men to stop, so that this city will not be rebuilt until I so order.
We obviously know that he was told a falsehood by the enemies of Judah and Ephraim about what was actually going on in Jerusalem in that they were not rebuilding city walls as Artaxerxes was led to believe, however, he stopped the process nonetheless.
Moving forward in history...we know in Ezra 6, after the death of Artaxerxes, construction restarted by Zerubbabel, and that King Darius was approached by Tattenai the governor of the region west of the Euphrates to confirm the decree to rebuild the Temple in Jerusalem. The response from Darius:
Exra 6:1 Thus King Darius ordered a search of the archives stored in the treasury of Babylon. 2And a scroll was found in the fortress of Ecbatana, in the province of Media, with the following written on it:
3In the first year of King Cyrus, he issued a decree concerning the house of God in Jerusalem:
Let the house be rebuilt as a place for offering sacrifices, and let its foundations be firmly laid. It is to be sixty cubits high and sixty cubits wide,a 4with three layers of cut stones and one of timbers. The costs are to be paid from the royal treasury.
5Furthermore, the gold and silver articles of the house of God, which Nebuchadnezzar took from the temple in Jerusalem and carried to Babylon, must also be returned to the temple in Jerusalem and deposited in the house of God.
6Therefore Darius decreed:
To Tattenai governor of the region west of the Euphrates,b Shethar-bozenai, and your associates and officials in the region:
You must stay away from that place! 7Leave this work on the house of God alone. Let the governor and elders of the Jews rebuild this house of God on its original site.
Ezra obtains letters from Artaxerxes and returns from Babylon
Ezra is granted authority by king Artaxerxes in the 7th year of his reign. However, it appears to me that the letter given to Ezra by the kind at that time is still only for Temple, its services, and for the self governance of Judah. It does not appear to make any reference to the rebuilding of the city itself.
Ezra 7:12 Artaxerxes, king of kings.
To Ezra the priest, the scribe of the Law of the God of heaven:
13I hereby decree that any volunteers among the Israelites in my kingdom, including the priests and Levites, may go up with you to Jerusalem. 14You are sent by the king and his seven counselors to evaluate Judah and Jerusalem according to the Law of your God, which is in your hand. Ezra7: 23 Whatever is commanded by the God of heaven must be done diligently for His house.
Some 12 or 13 years later, in the 20th year of Artaxerxes reign, Nehemiah the cupbearer asks the king for permission to rebuild the walls and gates of the city
Nehemiah 2:4 “...If it pleases the king, and if your servant has found favor in your sight, I ask that you send me to Judah, to the city where my fathers are buried, so that I may rebuild it.” 7 I also said to him, “If it pleases the king, may letters be given to me for the governors west of the Euphrates,b so that they will grant me safe passage until I reach Judah. 8And may I have a letter to Asaph, keeper of the king’s forest, so that he will give me timber to make beams for the gates of the citadel to the temple, for the city wall, and for the house I will occupy.”
My point of interest is the original prophecy in Daniel 9 stating restore and rebuild Jerusalem. The decree given by Cyrus is only for the Temple, then Nehemiah is given authority to build the city walls and gates.
Finally, remember the prophecy given in Isaiah 44):
26 who confirms the message of His servant and fulfills the counsel of His messengers, who says of Jerusalem, ‘She will be inhabited,’ and of the cities of Judah, ‘They will be rebuilt, and I will restore their ruins,’ 27who says to the depths of the sea, ‘Be dry, and I will dry up your currents,’ 28who says of Cyrus, ‘My shepherd will fulfill all that I desire,’ who says of Jerusalem, ‘She will be rebuilt,’ and of the temple, ‘Let its foundation be laid.’
Which of the above is the official decree that fulfills the explanation of the prophecy by the angel Gabriel in Daniel 9:25?
- The first decree given to build the Temple by Cyrus in 539 B.C and overseen by Zerubbabel (Cyrus lived 600-530 B.C)
- the second decree given by Darius the Great 522-486 B.C (what year was this decree given... 521 B.C?)
- The authority given to Ezra by Artaxerxes in 7th year of his reign (457 B.C)
- or the letters given to Nehemiah by Artexerxes to build the city walls and gates? (445 B.C)