Before the Great War occured, Lower Manhattan was defined most commonly as the area delineated on the north by 14th Street, on the west by the Hudson River, on the east by the East River, and on the south by New York Harbor (also known as Upper New York Bay). When referring specifically to the Lower Manhattan business district and its immediate environs, the northern border was commonly designated by thoroughfares approximately a mile-and-a-half south of 14th Street and a mile north of the island's southern tip: Chambers Street from near the Hudson east to the Brooklyn Bridge entrances and overpass.
Two other major arteries were also sometimes identified as the northern border of "Lower" or "Downtown Manhattan": Canal Street, roughly half a mile north of Chambers Street, and 23rd Street, roughly half a mile north of 14th Street. The Lower Manhattan business district formed the core of the area below Chambers Street. It included important financial and government institutions such as the Financial District (also known as Wall Street) and City Hall. The neighborhood of TriBeCa straddled Chambers on the west side; at the street's east end is the giant Manhattan Municipal Building. North of Chambers Street and the Brooklyn Bridge and south of Canal Street lay most of New York's oldest Chinatown neighborhood. Many court buildings and other government offices were also located in this area. The Lower East Side neighborhood straddles Canal. North of Canal Street and south of 14th Street were the neighborhoods of SoHo, the Meatpacking District, the West Village, Greenwich Village, Little Italy, Nolita, and the East Village. Between 14th and 23rd streets were lower Chelsea, Union Square, the Flatiron District, Gramercy, and the large residential development Peter Cooper Village—Stuyvesant Town in the eastern part.
When the Great War tore Manhattan and the rest of New York City apart, Lower Manhattan sustained the worst of the bombardment. Many of Lower Manhattan's greatest buildings, even its skyscrapers, were pulverized by Chinese bombs. The bombardment targeted the central part of Lower Manhattan primarily. As a result, that was where the most destruction was wrought and little to no buildings remain there, the epicenter of the damage being the now noexistent Canal Street. The lower tip of the island and the coast were luckier. Only a few notable buildings remain relatively intact there such as the New York Stock Exchange. The area now looks more like a rocky plateau than a Concrete Jungle.
Most of the other buildings collapsed to the ground, with some even going underground. This perfect storm of collapsed buildings, radiation, and other more mysterious factors produced a plethora of mutants soon after the war. These included ghouls, Radigators, and most importantly, Underlyers. Soon after their wicked birth, the Underlyers began making a honeycomb of burrows everywhere underneath and inside the ruins of Lower Manhattan before expanding elsewhere. That was why after exploring it, early wasteland explorers named the area the Hive.
The center of the Hive (TriBeCa, SoHo, and Lower East Side) is deathly radioactive and normally uninhabitable for humans. This has led it to spawn its own mutant ecosystem. Recently however, an offshoot of the Children of Atom has settled in the area, revering it as perhaps Atom's "holiest of holies". Also, a Reclamation outpost was recently built in the Hive to help harvest deathclaws, though it remains thinly manned.
On the northern and southern edges of the Hive where the radiation is lesser, human settlements have started to take root. The Libeterian colony of Battery Park and its fortified neighbor the New York Stockyard cling to the bottom of the Hive while various raider outposts and wasteland settlements stand in the north.
The few that dare to brave the surface of the Hive must be either immune to radiation, well-equipped to resist it, or have a death-wish. Even if a wasteland explorer or scavenger survives the radiation though, they must also confront the area's hostile mutant wildlife.