An architectural structure is a free-standing, immobile outdoor constructed element. The structure may be temporary or permanent.

Structures include buildings (occupied—habitable) and nonbuilding structures (non-occupied—non-habitable).

Often the words architectural structure and buildings are confused, because in many languages one word covers both. However, a building is a type of architectural structure used for supporting and sheltering continuous occupancy or habitation. Building structures (buildings) are therefore usually enclosed and/or roofed structures. Nonbuilding structures (structures) may be open to the environment, part of landscape design elements, and/or part of infrastructure systems (transport, water, energy).

Some structures are temporary, built for ephemeral events such as trade shows, conferences, or theatre, and often dismantled after use. Temporary structures have fewer constraints relating to future use and durability, and often comprise lightweight forms such as tents or reusable such as boxcars, which are quicker to erect, take down, and use at another site or recycle.