Tikrit, just 140 kilometres (90 miles) north of Baghdad is the political and sociological centre of gravity of Saddam Hussein's regime.
The war's final showdown could well take place in Tikrit
It is where he was born and it could turn out to be the Baathist Party's last stronghold.
If there is to be a final showdown in this war, then it could well happen in Tikrit.
Units of the Republican Guard's Adnan Mechanised Division are located in and around the town.
They have been under air attack for over two weeks. Regime targets, like headquarters, command bunkers and other places, have also been hit.
Tikrit was previously best known as the birthplace of the great Muslim general Saladin who battled the Crusaders during the Middle Ages and ejected them from Jerusalem during the 12th Century.
Before Saddam Hussein came to power in 1968, Tikrit was an isolated backwater
Before Saddam Hussein came to power in 1968, it was an isolated backwater.
Since then, it has grown into a town with a population of more than 260,000.
It boasts a Republican Guard garrison, an airfield and an Air Force academy.
Nearby is the largest and most elaborate of Saddam Hussein's presidential compounds.
But Tikrit's importance to the regime is less about geography or buildings than people.
Saddam Hussein's rule is based upon a tight network of family and clan ties that permeate all of the regime's main military,
security and political institutions.
A small group of clans or tribes from Tikrit and the surrounding area dominate the Baathist state apparatus.
This is Saddam Hussein's home turf in every sense of the term.
From winners to losers
The US war plan initially saw the 4th Infantry Division moving southwards from the Turkish border towards Baghdad.
It is not clear if it would have isolated and bypassed Tikrit.
But it would certainly have pinned down and engaged Iraqi forces in northern Iraq, including the three Republican Guard divisions based there.
As things turned out there was no major northern front.
The Republican Guard units appear to have been split up into brigade-sized formations, many of which moved southwards to engage US units moving on the capital.
They were badly mauled from the air and from their piecemeal engagements with advancing US mechanised forces.
How much actually remains in a formal sense is impossible to tell.
The town is also likely to be heavily defended by irregular militia or paramilitary units loyal to the regime.
They could put up stiff resistance, not least because these die-hards have nowhere else to go.
How far local people will support them is also unclear.
These were the winners under Saddam Hussein's rule.
Now, by any assessment, they are the losers.
US troops could make some probing attacks into Tikrit within a matter of days, possibly from the north-east.
But if it looks as though there is going to be a major fight, it will be left to the 4th Infantry Division that has been unloading its equipment in Kuwait.
Its advance brigade will be in the field within a few days.
The stage is being set for what could be the last major battle in this war.
There is an historical precedent.
The last major engagement during the British Army's Mesopotamia campaign during World War I was near Tikrit in 1917.
And that too came after Baghdad had fallen.