When he was invited to exhibit at Palacio de Cristal, the Kosovo-born artist Petrit Halilaj was encouraged to produce “the piece of his life.” What he came back with was unexpected, monumental, and biographical. He installed structures, opened windows, and set up feeding areas, transforming the interior and exterior of the Palacio into a giant nest for birds and other creatures in Parque del Retiro. Flowers decorate steel frameworks and elaborate, colorful structures dot the area, designs inspired by the bowerbird species, whose male builds a decorative nest, or bower, as part of its courtship ritual. Halilaj’s installation brings together nature and culture, and also celebrates his relationship with his partner, the artist Álvaro Urbano. This nest is a home for diversity. —E.C.