[x]

The photos are mostly of buildings in the concrete "brutalist" style.

Not all modernist (or post-modernist) buildings are like that.

[Dr. Sivana]

The photos are mostly of buildings in the concrete "brutalist" style.

Modern is being used in a broader sense, just as many composers are called classical who are technically calssical composers, but are easily distinguished from rock, hip-hop, blue grass and jazz.