Pietri Architects has driven a deep pink ravine through the heart of this apartment complex in southern France, creating a protected rooftop garden for residents (+ slideshow).

Named after the vivid pink-red paintwork that brackets its central garden, the Redline apartment block was designed by Parisian studio Pietri Architectes to create 59 flats of varying sizes, split across two towers.

The blocks rise from a solid single-storey base containing a car park and business premises. The narrow slice of greenery sits above, affording sea views between the towers.

The building came about as part of a wider regeneration of the former shipping city of La Seyne-sur-Mer on the south-east coast of France, where dockyards closed in 1989.

The dockyards will be rejuvenated with a public park named Autumn Garden, which the apartments will also overlook.

"The Redline plot could not have tolerated a single, solid block," said the architects. "[This] would have obstructed the views of the surrounding housing and prevented half of the 59 housing units from having a view of the sea."

The long rooftop garden runs east to west through the centre of the site. "This east/west spatial organisation grants a multiplicity of amenities with apartments that have both front and rear facing views and an outdoor patio designed to ventilate and make the most of the vista," said the team.

Brightly coloured walkways built from pre-stressed concrete criss-cross the void to connect the two blocks on every level. They primarily allow residents in the east block to access the lifts, which are contained on the west side of the complex.

These walkways are enclosed with mesh balustrades and feature wooden floor surfaces. Strip lighting is set into the underside of each one to illuminate the spaces below.

Below the walkways, the planted oasis of gardens and terraces is screened from the prevailing south-westerly winds by the high concrete walls.

Pathways cut through a series of raised planters filled with grey gravel and a variety of evergreen trees and spiky shrubs. They lead to a sunken seating area and a red concrete belvedere, which is raised above the gardens on a metal pole and accessed by a flight of steps.

The podium has one open side that angles towards the sea, offering a sheltered outdoor seating spot for residents.

Small deep-set windows face into the pink courtyard, while larger windows in the cream-painted facades of the two blocks are directed towards the coastline.

White balustrades with a perforated pattern enclose private terraces on the street-facing aspect of each apartment. The balustrades curve around the corners of the blocks to give the buildings a rounded profile.

"The patio, belvedere and walkways invite contemplation of the landscape – on one side the Autumn Garden and on the other the Bay of Toulon," said the architects.

Dark pink and white stripy dividers, reminiscent of the material often used on deck chairs and bathers' windbreaks, separate each balcony from its neighbour. They provide storage lockers for residents.

Photography is by Serge Demailly and Christian Michel.

Project credits:

Client: Constructa
Project management: Pietri Architectes, BET Yves Garnier, BET Qualiconsult, Marseille aménagement, Néo Paysages, Veritas