Architecture in Beowulf, which can loosely be described as any structure that is made by man rather than nature, has several emblematic meanings. First, architecture—most often represented by mead-halls—is a ruler's seat of power and is synonymous with a leader's throne room, that is, his right to rule.
Second, it represents mankind's control over a generally hostile nature: the "fens and fastness" in which Grendel and his mother live, the hostile sea in which Beowulf and Breca fight sea snakes, and the barrow in which the dragon lives and in which Beowulf is mortally wounded. For example, even though Grendel and his mother are able to penetrate Heorot, the hall of the red deer, the hall itself is still standing after their onslaughts—proof that the architecture of man can withstand whatever evil nature creates.
The importance of architecture as a ruler's seat of power is made explicit at the beginning of the poem:
Often Scyld Sheaf-child scattered his enemies,
captured their mead-halls and cowed their leaders. (2.4–5)
Because the mead-hall represents a warrior-king's center of power, its destruction or occupation by a victor is the ultimate sign that a new warrior-king has taken control of the tribe and its lands. In a culture in which tribal strife is endemic, the mead-hall is both a stronghold and a liability: it is built to be defensible, but it is also an important target for an enemy because of what it represents.
It is commonplace for cultures to think of their architecture as symbols of power—consider the Eiffel Tower, the Arc de Triomphe, the Brandenburg Gate, the Sphinx, the Coliseum—and the Scandinavians and Anglo-Saxons have their (albeit) more humble mead-halls as their symbol of power over other tribes as well as a defense against hostile nature.
That the mead-hall is the ultimate symbol of power in the Scandinavian/Anglo-Saxon belief system, whether pagan or Christian, becomes quite clear when the poet describes Hrothgar's great mead-hall, Heorot:
...To his mind it occurred
that he would have a longhouse raised,
a greater mead-hall made by men
than any man-child ever had heard of. (2.67–70)
Significantly, the poet focuses on two important elements of Heorot: it is "made by men," not nature, and it is the best that men have "heard of"—a hall befitting a king, Hrothgar, and the people he leads.
A mead-hall, however, is just a building until it becomes, in the world of Beowulf, the center of the community and, more important, the distribution point of wealth for Hrothgar's men:
He [Hrothgar] broke not his vow,
but dealt out rings and treasure at feasts. The hall towered high and horn-gabled. (2.81–82)
This piece of architecture is central to the Scandinavian/Anglo-Saxon feudal system, which begins with the warrior-king distributing wealth to his loyal retainers, with the best warriors receiving the greatest share of captured valuables from their latest fight with another tribe. In a warrior society, loyalty is valued as highly as gold, and this loyalty is created on the battlefield and in the mead-hall.
The significance of the mead-hall as a permanent and powerful fixture on the landscape is made clear when, after Beowulf's struggle with Grendel, in which Grendel has his arm and shoulder severed by Beowulf, we read:
That was a clear token,
after the warrior [Beowulf] laid down the hand,
arm and shoulder: there in one piece
was Grendel's grasp, under the great roof. (2.833–836)
It is altogether fitting that the emblem of Beowulf's victory over the monster who plagues Hrothgar's mead-hall is displayed under the gabled roof of Heorot—a triumph of mankind and his architecture over evil.