Inside the National September 11 Memorial, due to open in a month, stands a pear tree that is still charred from the terrorist attacks a decade ago, but has sprouted new branches.  Dubbed the "Survivor Tree," it was nursed back to health at a park in the Bronx. It is symbolic of the horrors of 9/11 — and of the rebirth of the 8-acre World Trade Center memorial site and Lower Manhattan itself.  Construction workers are toiling to ready a tree-lined plaza and two pools constructed in the footprints of the towers toppled by hijacked commercial jets on 9/11. The pools, with 30-foot waterfalls cascading down four sides before the water is sucked downward, are topped with panels etched with the names of the nearly 3,000 people who died in the attacks in Manhattan, Pennsylvania and at the Pentagon, plus those killed in a 1993 WTC bombing.  Names, to be lighted at night, will stay covered until unveiled to families of the fallen in a dedication ceremony Sept. 11. Public viewing starts the next day, via free timed tickets. Up to 4 million visitors are projected in the first year. An uncompleted museum on the site, to house 9/11 artifacts such as fire trucks and photos and remembrances from family members, is due in September 2012.  More than a memorial is rising. "We want people to see the rebuilding and renaissance" of the WTC site and "to go and pay your respects," says George Fertitta, CEO of NYC & Company, the city's tourism and marketing arm. He hopes visitors will stay to see "the revitalization of downtown" and Lower Manhattan — once quiet after the business day was over — as an attraction-packed destination and place to stay. NYC & Company is running a Lower Manhattan promotion that includes hotel discounts to encourage out-of-towners to check out the city's increasingly lively southern tip.  WHERE TO STAY: Be aware that the new W New York-Downtown and the Millenium Hilton adjoin the World Trade Center construction site (the Hilton has sued WTC developers for lost revenue). If noise bothers you, ask for the back or wait till the Sept. 11 memorial and museum are done. Budget-friendly options near the WTC include the Best Western Seaport Inn (premium rooms with terraces overlook the Brooklyn Bridge). Rates start at about $159, plus tax, and include breakfast and Wi-Fi. 800-468-3569; seaportinn.com. The year-old Holiday Inn Express New York City-Wall Street has small modern rooms in the same price range, including a hot breakfast and Wi-Fi. 888-465-4329; hiexpress.com.WHAT TO SEE: National September 11 Memorial (free timed tickets: 212-266-5200 or 911memorial.org). Also in the area: the Tribute WTC Visitor Center, from the September 11th Families’ Association, with photos, remembrances and artifacts; South Street Seaport; Battery Park; Statue of Liberty (the statue closes for a year of renovations Oct. 29, but Liberty Island stays open); The New York City Police Museum; National Museum of the American Indian; The Skyscraper Museum; Governors Island.INFORMATION: 212-484-1222; nycgo.com. Through Sept. 6, NYC & Company is running a “Get More NYC: Lower Manhattan” promo with weekend hotel deals, free museum admission, and more.  Indeed, the area that runs from Battery Park on New York Harbor to Chambers Street just north of the WTC site, has undergone a transformation. An estimated 9 million visited in 2010, up 26% from 2008, the Alliance for Downtown New York says. Lower Manhattan's population has more than doubled since 9/11, to 56,000 in 2011, it says, due to the area's increased desirability, shops and restaurants and new apartment buildings — including one designed by Frank Gehry.  Ten years ago, six hotels catered mostly to weekday travelers with business in the city's financial district. Now — with an office building boom downtown (the Condé Nast publishing giant, for one, will be moving into a new World Trade Center tower under construction) and more visitors — there are 18 lodgings, including a new Andaz, W and Holiday Inn Express. Hilton's upscale Conrad brand is due. Guests say the area is less chaotic than Midtown, but just a quick subway ride away, reports Holiday Inn Express general manager Jessica Davila.  But there's no lack of downtown attractions. South Street Seaport, a museum/shopping/restaurant complex on historic piers, has shops, restaurants and the new Beekman Beer Garden Beach Club, which at night offers a closeup of the necklace of lights on the Brooklyn Bridge and a club atmosphere. It has a small manmade beach on a deck above the river — a big square of sand in which patrons dip their toes and sip cocktails till 3 a.m. while lounging on white plastic sofas lighted from inside.  Cafe life thrives on Stone Street  On surrounding cobblestone streets, young Wall Streeters and locals form a scrum on the sidewalk, socializing over pints at pubs such as New Zealand-themed Nelson Blue. Sidewalk cafes whose tables fill lively, pedestrian-only Stone Street dish up fare from Greek, to Italian, to all-American. Just try to snag a seat at 12:30 on a weekday at Adrienne's Pizzabar, where rectangular $17.50 thin-crusted pies delivered on metal trays are scarfed by financiers. (Sadly, you can't go into the guarded New York Stock Exchange unless you have special authorization, due to post-9/11 security fears.)  Streets are narrower than those uptown, trees fewer (but there are parks, and about 400 oaks will grace the September 11 Memorial plaza). Save when the Stock Exchange is open or Chinese restaurant delivery men careen on bicycles ferrying takeout to apartment dwellers, the pace downtown is slower.  But not if you happen on a shopaholics' draw on Cortlandt Street near the WTC site. A motto of Century 21 discount department store, luring locals and tourists from around the world: "fashion worth fighting for." Bargain hunters battle for merchandise marked down to jaw-dropping depths ($10 for jeans that usually would be $70). Shoppers shamelessly slip on clothes in the aisles, wait a half-hour for a dressing room and dash to join the queue for cash registers.  The scene is just as hectic at the 9/11 memorial on a recent day, as hard-hatted workers hammer and confer, truck back-up warnings beep and cement mixers swirl. Lynn Rasic, the memorial's senior vice president for public affairs, picks her way over construction cables and says that so far, more than 260,000 people have requested free tickets — from every state and more than 40 countries.  Tourism officials portray the memorial as a place of respect for the fallen, a symbol of New Yorkers' resilience, and they discourage the term "Ground Zero" as negative. Rasic hopes the memorial will be a tranquil place of remembrance. Behind her in a nearly completed pool, waterfalls trickle symbolically into an unseen void below.
With the Sept.11 Memorial opening in a month, we tour and take a look at the renaissance of Lower Manhattan