Really good explanation of 2520

Ezekiel 2520 yrs.

The Prophet Ezekiel was to act out prophecy with strange per­for­mances, one of which was to lie on his side for a total of 430 days.  Each day on his side would rep­re­sent 1 year of  judg­ment on Israel.
Ezekiel 4:4 Also lie on your left side, and lay the iniq­uity of the house of Israel on it; accord­ing to the num­ber of days that you shall lie on it, you shall bear their iniq­uity. For I have laid on you the years of their iniq­uity, accord­ing to the num­ber of the days, three hun­dred and ninety days. So you shall bear the iniq­uity of the house of Israel.  6 And when you have ful­filled them, lie again on your right side, and you shall bear the iniq­uity of the house of Judah forty days; a day for a year; a day for a year, I have set for you.
So we see he is told about 390 and 40 years of judg­ment for a total of 430 years.  Each day was expressly to rep­re­sent a year of judg­ment against the nation.  Now we know they did 70 years in Baby­lon­ian Cap­tiv­ity, as part of the pun­ish­ment for not let­ting the land rest.  That leaves 360 years (430 minus 70 time served) unac­counted for.
The 360 years do not seem to fit any period of Israel’s his­tory.  It has been sug­gested by some that there might be a clue in Leviti­cus 26, where God indi­cates that: …if ye will not yet for all this hear­ken unto me, then I will pun­ish you seven times more for your sins. — Leviti­cus 26:18.  So if we take 7 times  the 360 years we end up with (7x360) = 2520 years.
These  “prob­lem” 360 years by seven yields 2520 years, is “approx­i­mately” the dura­tion of time from the exile of Judah to the final re-establishment of Israel in her own land,  some two and half cen­turies later.
Sir Robert Ander­son, in his clas­sic work The Com­ing Prince, noted that the Bible uses 360-day years in both Gen­e­sis and Rev­e­la­tion. We call that a prophetic year.
In attempt­ing to rec­on­cile the 2520 of 360-day years to our Roman cal­en­dar, one is faced with the dis­crep­an­cies between the side­real year and the solar year.  In 1572, it was rec­og­nized that errors had accu­mu­lated to 11 days too many, and adjust­ments were required.
In the Gre­go­rian Reform, Sep­tem­ber 4th was declared Sep­tem­ber 14th, and the for­mula for leap years was changed to exclude cen­turies unless divis­i­ble by four (and mil­len­nia by 400).
So 2520 years of 360-days each con­tain 907,200 days, which are equal 2483 years, 9 months and 21 days on our to cur­rent solar calendar.

2520 years  x 360 days in a year = 907,2000 days.

Another prob­lem occurs when we exam­ine more closely the “Baby­lon­ian Cap­tiv­ity.”  There are two dif­fer­ent inva­sions that are candidates:
1) “Servitude of the Nation,” in 606 BC.
2) “Desolations of Jerusalem.” in 587 BC
Each of these was proph­e­sied to be sev­enty years in dura­tion and most peo­ple think they refer to the same time.   There were actu­ally three sieges of Neb­uchad­nez­zar upon Jerusalem.
Servi­tude of the Nation in 606 BC.
The first siege began the “Servi­tude of the Nation” and was proph­e­sied to last 70 years.
The first siege of Neb­uchad­nez­zar, in 606 B.C., began the “Servi­tude of the Nation,” which lasted until the sum­mer of 537 B.C.  The inva­sion of 606 B.C. left Jerusalem intact with a vas­sal king installed..
If we count from the Fall of the Nation  end­ing  70 years later a total  907,200 days we arrive at May 14^th 1948.   On May 14, 1948, the nation Israel was reestab­lished on the world scene. But it did not include all of Jerusalem.
Des­o­la­tions of Jerusalem in 587 BC. The third siege of Neb­uchad­nez­zar, in 587 B.C., began the “Des­o­la­tions of Jerusalem,” which lasted until 518 B.C. If August 16, 518 B.C. was the com­ple­tion of the walls of Jerusalem.  The vas­sal king that Neb­uchad­nez­zar left later rebelled; a sec­ond siege resulted in his uncle, Zedekiah, being appointed to the throne. The prophets Jere­miah and Ezekiel both went on to warn that if they per­sisted in rebelling against Neb­uchad­nez­zar the city of Jerusalem would be destroyed. Zedekiah ulti­mately yielded to the false prophets and rebelled.
A third siege resulted in the destruc­tion and des­o­la­tion of the city of Jerusalem in 587 BC.
The “Des­o­la­tions of Jerusalem” also lasted 70 years, until Nehemiah ulti­mately suc­ceeded in get­ting the author­ity to rebuild the city of Jerusalem. This, too, was pre­cisely 70 years.
The third siege of Neb­uchad­nez­zar, in 587 B.C., began the “Des­o­la­tions of Jerusalem,” which lasted until 518 B.C.  If August 16, 518 B.C. was the com­ple­tion of the walls of Jerusalem, then 907,200 years later puts us at June 7^th 1967.
On June 7, 1967, as a result of the Six Day War,  the Bib­li­cal city of Old Jerusalem was restored to the nation.
It should be borne in mind that the “start­ing” dates are not known pre­cisely to the day.  Behold, he that keeps Israel shall nei­ther slum­ber nor sleep. — Psalm 121:4