The Pentagon building has five congruent sides. We are given that one side is $921$ feet long. We need to find the perimeter of the Pentagon.

1. Problem Description

The Pentagon building has five congruent sides. We are given that one side is $921$ feet long. We need to find the perimeter of the Pentagon.

2. Solution Steps

A pentagon has 5 sides.

The perimeter of any polygon is the sum of the lengths of all its sides.

Since the Pentagon has five congruent sides, the perimeter is simply 5 times the length of one side.

Given that the length of one side is $921$ feet, the perimeter is $5 \times 921$.

$Perimeter = 5 \times side$

$Perimeter = 5 \times 921$

$Perimeter = 4605$ feet

3. Final Answer

The perimeter of the Pentagon is $4605$ feet.