Its entrances are reportedly mined, the streets and alleys bristle with armed fighters from Moammar Gadhafi's tribe. This is Sirte, Gadhafi's hometown _ the halfway point between the rebel capital and Tripoli and a major obstacle on the opposition's march west.
It will not be easy for rebels to take the Mediterranean coastal city. Gadhafi's tribe is the most powerful in the city of some 150,000, which is guarded by an elite unit led by one of his sons.
But with swift battlefield successes made possible by U.S. and European airstrikes and the enforcement of a no-fly zone, the rebels' chances look better than at any time since the uprising began in mid-February to demand an end to Gadhafi's 41-year rule. Opposition commanders are hoping that dissident tribes within Sirte will rise up to help them as their forces move in on the city.
On Monday, Libya's rebel forces closed in on Sirte, storming to a point about 80 miles (120 kilometers) to the east, after the city was targeted for the first time by international airstrikes. Blasts from strikes were heard late Sunday and around 6:30 a.m. local time Monday, witnesses said but they did know what was hit.
Armed Gadhafi supporters were roaming Sirte's streets, the witnesses said. The men were mostly in civilian clothes and many wore green bandanas to show their loyalty to Gadhafi.
Allied strikes hitting regime forces' armor and shutting down their air force evened the odds in terms of firepower, said Gen. Hamdi Hassi, a commander of army units that joined the rebellion. "Because of NATO strikes on the heavy weapons, we're almost fighting with the same weapons, only we have Grads (rockets) now and they don't," Hassi told The Associated Press at a town just east of the front line.
He said the opposition was trying to get in contact with potentially anti-Gadhafi tribes inside Sirte. Members of the powerful Firjan tribe are believed to have long resented the domination of the Libyan leader's Gadhadhfa tribe. Other tribes in the city are thought to be on the fence, waiting to see who has the upper hand. "If they rise up it would make our job easier," Hassi said.
Sirte is roughly halfway along the 625-mile (1,000-kilometer) road between Tripoli and the opposition stronghold of Benghazi in the rebel-held east of the country.
"Sirte is the key to Tripoli and it will be a big and difficult battle to seize it," said Ahmed al-Muqassabi, a 20-year veteran of Libya's state radio who defected to the rebels' cause after the uprising began.
Over the years, Gadhafi has effectively turned Sirte into a second capital, spending millions of dollars to build conference halls and hotels to use it as a venue for Arab and African summit meetings.
A sleepy town, Sirte has traditionally been a trading and agricultural community, surrounded by farmlands, though under Gadhafi it has been filled out by large numbers of government employees. It comes alive only when Gadhafi hosts summit meetings in its luxurious convention center, with limos and police cars and motorcycles dashing down the tidy road from the airport to the center, their sirens wailing.
Libyans familiar with Sirte say its first line of defense is a heavily fortified area called the al-Wadi al-Ahmar, 55 miles (90 kilometers) east of the city.
"I think the next fight will be in al-Wadi al-Ahmar because it's the entry to Sirte," 31-year-old Suleiman Ibrahim, a volunteer for the rebels, said Sunday.
"We expect a big fight in Sirte, but we will win, God willing. This couldn't have happened without NATO, they gave us big support," he said as he sat in the back of a pickup truck next to a friend carrying an RPG. Opposition fighters on Sunday took back two key oil complexes east of Sirte.
The rebels have been hampered by their own lack of a command structure and the poor discipline of their volunteer fighters, mostly young men in their late teens and early 20s who routinely rush toward enemy lines only to retreat under the first shells.
Whether they can capture Sirte depends on how Gadhafi organizes its defenses. Deploying his troops out in the open outside the city would make them easy targets for Western warplanes. Keeping them in built-in areas inside the city would mean prolonged and bloody fighting, with the international force barely influencing the outcome.
Gadhafi's tribesmen have a vested interest in the regime's survival _ and the continuation of the largesse he has shown them over the years, said Libyans contacted by phone from Cairo. The Gadhadhfa are heavily armed and use the city's air base as the headquarters of a militia drawn from their ranks.
Other tribes, including the Firjan, may be the key to the city's fate.
The handcuffed bodies of 20 Firjani army officers were found by rebel forces when they captured the oil port of Brega early this month. They presumed that the 20 refused to fire on the rebels, and they expect that the execution-style killings may have angered many members of the tribe enough that they would welcome the arrival of the rebels to rid them of the pro-Gadhafi forces. It was impossible to independently confirm the executions.
A failed coup against Gadhafi in the 1990s was led by a member of the Firjan. The attempt brought harsh reprisals from Gadhafi's regime _ some Firjan were executed, and jobs and perks were taken away from others.
The other major tribes in Sirte _ Zayaynah, Hamamlah, Hassoun and Meaadan _ have been neutral and would probably just stay home in any fighting, according to the Libyans, all of whom spoke on condition of anonymity because they feared reprisals.
"We know it will be difficult to get Sirte," said Moataz Tajouri, a 24-year-old rebel fighter from Benghazi who was pushing west on Sunday. "But we are willing to die to liberate it."
Associated Press reporter Ryan Lucas contributed to this report from Ras Lanouf, Libya