Portsoken Pavilion is the centrepiece structure in a new landscaped public square commissioned by the City of London Corporation that has replaced the former Aldgate gyratory. The small building is a part of a larger civic aim to provide space for events and leisure and improve wellbeing.

The new pavilion was to have an aesthetic relationship with the City of London Information Centre, which was also commissioned by the client as well as to improve the connection for the two listed heritage buildings on either side of the square: the St Botolph without Aldgate church and Sir John Cass’s Foundation Primary School.

The City of London Corporation undertook extensive public consultation and the tenant – social enterprise café Kahaila - were involved in the design process to ensure it would be fit for purpose. The pavilion functions as a multi-use space for community events with regular yoga classes, church groups and other community groups using – or planning to use – the building.

Portsoken pavilion picks up on the asymmetrical angles of its predecessor, with a monocoque structure that folds down to meet the ground at just three points, with glazing in between. Designed parametrically, corten cladding panels form a rigid structural skin, a faceted surface that reduces the overall profile of the pavilion and provides its character. The channels created by the layered cladding are also functional, allowing the rainwater to run down them into discreet drains located where the steel meets the Yorkstone paving.

The warm tones of the weathered steel chime with the brown brick of the church and the red brick primary school. Over time the steel will darken and provide an earthy, complementary counterpoint.

It is a single storey above-ground, its three glazed elevations face the key pedestrian approaches to the new square and provide clear views into and through the structure delivering natural surveillance.

Internally the bands of the cladding are mimicked on the soffit, with layered geometric white laminate timber panels, which have punched slots to aid the acoustics and, when up-lit at night, provide a glowing effect to the whole building. Two large asymmetrical rooflights draw light into the building. Outside, the roof overhangs the entrances to allow seating to spill out.

Make took the opportunity to utilise part of the former subways to accommodate a 200 sqm basement level for plant, back-of-house facilities, kitchens and toilets. This has significantly reduced the ground floor footprint and therefore delivered more public space.

The constant temperature of the concrete tunnels help regulate the temperature of the building: air is drawn through the tunnels and up into the café, heating it in the winter or cooling it in the summer. The large overhangs on the roof are also attuned to the orientation of the sun and provide solar shading to the interior at peak times of the day.

The project is both sculptural and functional. It acts as a piece of art and a community hub in the new public space and, despite its small size, is designed to have a big civic impact.