Level Up is designed to be a new place for locals in the post industrial port city to socialise, and turns a previously disused rooftop area into a terrace.
The international quartet of architects created the site-specific pavilion as part of European Architecture Students' Assembly, (EASA) 2018.
The pavilion was built as an extension to Export Drvo, a 1950s industrial storage building by the Dead Canal. Rijeka is due to become Europe's culture capital in 2020, and the Export Drvo is set to be one of the key venues in the celebrations.
The pavilion, which doubles as street furniture, is formed of a series of levels linking up to a elevated terrace built on the roof.
Different places and surfaces for visitors to sit, swing or relax in a hammock are placed all along the extended staircase to the top of the structure.
On the terrace a platform provides a raised vantage point to look over the city and doubles as a place for speakers to address a crowd.
Mahon, who is from Northern Ireland, Parviainen from Finland, and India-based Tulshan and Sett, drew up the design prior to EASA 2018, where they ran a workshop for participants who helped bring Level Up to life.
"Instead of creating new public urban area, Level Up puts focus on reclaiming existing space," said the design team.
"It creates a balcony to the Delta with an industrial aesthetic, acting as a public frontage. In an era where permanence of the built form has been defining architecture, Level Up celebrates ephemeral urbanism, inviting everyone to ponder material and spatial impermanence."
Steel scaffolding was used for the structural frame, with wooden boards and decking used to create the levels, steps and furniture. Plants sourced from a local garden centre were used to decorate the pavilion.
Others repurposing unused places for public space include Jordanian architects Sarah Abdul Majid and Sandra Hiari, who have designed a series of stackable wooden units that can turn abandoned areas into children's playgrounds.
Photography is by Rahul Palagani.
Designers and tutors: Brett Mahon, Joonas Parviainen, Saagar Tulshan, Shreyansh Sett, Vanja Borovic
Participants: Ana Mateos, Anna Opitz, Аnton Fedin, Ásta María Thorsteinsdóttir, Ayşe Tuğçe Pınar, Birgit Fløystad, Caro Andrade, Ciaran Magee, Chloë Reyda, Felic Micallef, Gleb Rudenya, Glenn McNamara, Gustavs Grasis, Ilia Bebi, Joanna Lewanska, Julia Triches, Julien Hermant, Klemen Mraz, Mattea Fenech, Samúel Aron Laufdal Guðlaugsson, Sebastian Bidault, Simona Svitkova, Tadhg Spain.