Adrián Villar Rojas, Sackler Serpentine Gallery

A queue of artists, press and glitterati snaked its way through Kensington Gardens waiting to be let into the private view for the opening of the Serpentine’s new Sackler Gallery this week, housed in The Magazine, a former 1805 gunpowder store, located a few minutes’ walk from the Serpentine Gallery on the north side of the Serpentine Bridge.

The Serpentine Gallery, supported by the Sackler Foundation, an education charity, along with the Bloomberg Foundation, outbid Damien Hirst who wanted to use the Grade II listed building to show off his private collection by the likes of Jeff Koons and Francis Bacon.

Attached to the original building is a new structure designed by Pritzker Architecture Prize laureate Zaha Hadid that will function as a restaurant. A sort of large luminous wedding marquee, the sweep of its domed arches is somewhat marred by the fact that the "awning" (pictured below © 2013 Luke Hayes) has puckered in places and not been pulled quite taut against the underlying armature. The Magazine itself, which was in military use until 1963, is rather stunning. It comprises of two raw-brick barrel-vaulted spaces (where the gunpowder was stored) and a lower square-shaped surrounding structure with a frontal colonnade. The removal of all non-historic partitions has created a space where the flat gauged arches over the entrances have been reinstated and the historic timber gantry crane maintained.

This forms a sympathetic milieu for the inaugural site-specific installation by the Argentinian artist, Adrián Villar Rojas. Rowed on shelves like objects from a fantasy museum Villar Rojars has created sculptures that suggest artefacts from some invented antiquity or imagined future. Drawing on an eclectic mix of influences from comic books to quantum mechanics, clay is the chosen medium in which he plays with notions of history, narrative, and modernity. And it was hard, among the crowds, not to feel some empathy for his huge elephant that, head down, seemed bent on escaping from the throng (main image).

The floor, which has been laid with handmade bricks, looks striking. While it implicitly makes reference to a traditional brickworks in Rosario, in Villar Rojas’s native Argentina, and does worthy things such as flag up the politics of a global economy, it wouldn’t look out of place on the front page of Interiors.

Down the road at The "old" Serpentine Gallery is the first solo exhibition in this country of the artist Marisa Merz, born in Turin in 1926. The only woman to be affiliated with the poetic and influential Turin-based Arte Povera movement – where "poor" and "found" materials were used to make art, often with a basis of political protest - there is a subtle feminist sensibility to her work. Her series of Living Sculptures, suspended clusters of forms made up of moving aluminium shards, are both industrial and ethereal: a modernist agenda with a poetic edge.

• Adrián Villar Rojas at the new Serpentine Sackler Gallery and Marisa Merz at The Serpentine until 10 November