What sustained him was the feedback on the ground. He could see as the Archive House led to the Listening Room, which led to the Black Cinema House, that his projects were answering a need that wasn't being met anywhere else. He says: 'There were these really quiet moments in the Archive House where we'd have a meal followed by some live music followed by a movie followed by more music. And at the end of that night, just to see people's elation... That's what was so exciting. They were thinking: "I can't believe this is in my neighbourhood. This is right down the road from where I live." And so those responses are far more interesting to me than any national attention.

Chicago's 19th-century Stoney Island Bank building was up for demolition until Gates bought it. Photo Credit: Tom Harris

'Another way of thinking about it is, my Mom has all these phrases and one is: "From those to whom much has been given, much is required". Because Chicago is kind of a small city still, my footprint there is quite large. How do you keep from becoming another kind of institution? You just keep distributing it. You've got to keep giving it away. That's been my resolve. If there's any sense of artistic leadership, it's like: Oh, you can use these moments of opportunity to demonstrate what it looks like to be generous. What does that look like? Because we don't know. Wealth isolates itself -- over there, around other wealth. White wealth goes over here. Asian wealth goes there.

Its purchase and restoration was funded by pieces of its marble floor being sold as 'bond certificates' at Art Basel. Photo Credit: Tom Harris

'You have these enclaves. And rarely do people grapple with what it means to stay. And... the part that people don't see is that it's fucking difficult. When my neighbour sees me she says: "What country are you going to tomorrow?" because she knows I'm going away. And I say, "Well, the UK." And she says: "When are you going to China?" -- and she's joking -- and I say, "Well, I'm going in January." And so we've had to create a way of relating that makes the craziness of my life and the ordinariness -- she might say -- of her life, that there's still a place for us to meet... I have come to cherish that but it means being in a neighbourhood, committed to relationships. Not committed to the ascendancy of it all. There's always a way to keep you on the ground. It's great.'

Among the new uses of the former Stoney Island State Savings Bank building in Chicago is a library. Photo Credit: Steve Hall

Being collaborative and participatory also helps keep his practice grounded and at the same time fluid -- the buildings thrive or fail on the human activity inside them. And this is one area that has yet to be tested: will these cultural centres, powered by his artist's sensibility and his passion to buck the system -- equal parts acts of faith and protest -- have the same traction 10 or 20 years down the line? Never mind the pernicious effect of regeneration that often acts to displace the original community; urban history is littered with impressive grass-roots projects that have not lasted beyond the proximity and engagement of the first generation of leaders. Thankfully for Gates, it's too early to say -- and the programme keeps rolling, with a host of new projects lining up in the 'rust-belt' cities surrounding Chicago and within it.

Longevity is not a problem that affects Sanctum, which only has to last 24 days. Gates' presence in Bristol sprang from an invitation by Claire Doherty, Situations' director, who played a major part in programming the art for Bristol's Green Capital 2015 year, and had some extra Arts Council cash to spend on something significant. She says: 'I was looking for someone who wouldn't be responding to the ideas behind Bristol 2015 in a literal way, but interested in the future of our cities and the resilience of our cities, coming at it from a very different point of view.'

Over coffee in Gates' Chicago HQ in 2013 they hatched their collaboration, with Gates directing the spirit, tone and look of the proceedings and Doherty and her team doing the work on the ground that would make this a truly Bristol initiative. Gates says: 'The Situations team has been so amazing, because it [its involvement] meant, in addition to what architecture can do, it's really about the power of the people.'

'This is the conversation I've been wanting to have with the architecture and design community,' Gates continues. 'Unless we invest more thoughtfully in people's voices and the great potential of those voices and abilities, we are still going to be making half-assed architecture. It could be so much smarter.' Gates wants both ordinary citizens and creatives to step outside their comfort zones and get more involved in the process of city-making. 'You know, there have been these periods in my art practice where I have had to ask: 'What else do I need to learn or understand in order to get the larger project done?

There were times when I had to pick up a new set of skills. [But] the unwillingness that artists and architects and designers have shown to understand the market has meant that we have largely been left out of the potential ethical decisions and the better design decisions we could make if we were the lead developer.

So do we wait for the developers to call us? If we choose not to learn that part of the world and we believe fully that the development world can only be evil, this [becomes] a self-fulfilling taboo. We can't be afraid of the tools of our city.'

Though city mayors are now beating a path to his door, Gates has not become enamoured of the species (Chicago's and Bristol's being among the few exceptions): 'I think that mayors especially are, like, "Just slap some art on it. Bring art to the city [then] we can get the gays and the artists", and it's a real parochial, unnuanced approach.' But then he says: 'You know there's a mayor in Gary, Indiana -- Karen Freeman Wilson.

The now renamed Stoney Island Arts Bank building also houses a museum, archive, exhibition space and artist resource. Photo Credit: Tom Harris

She is amazing. She's had a difficult time attracting both culture and economic development, and it's kind of left her city heavy. So she was so open to [the proposal] that art should connect to the department of environment, and housing and urban development... Anyway, my point is: there has to be deeper connectivity between culture and the other divisions of city making.

How can we encourage developers to not just get a tax credit so that they can build three more storeys if they have 500 sq ft or 500 sq m of art space? How do you imagine a new kind of building that really considers people and affordability, and not just destinations for tourists. I think both can be done.'

Gates must be getting used to seeing at least some of his dreams of community empowerment turn to reality, but he isn't done with protesting -- not by a long chalk. Sanctum is built with wall and roof joists from Victorian warehouses and factories whose labour and profits came directly from slavery and the sugar trade. Gates was keen to incorporate that part of Bristol's history in Sanctum; but he seems remarkably forgiving about it. 'Well, I'm not angry,' he says. '...bad history happens all the time... So, how do you do good with these bad moments? And how can these devastations convert themselves into something redemptive? I'd like to think that, for the black labour that's loaded in those boards, they would be able to rejoice in the fact that a black American was able to come over here and do amazing things with those materials.'

The overt, reclaimed aesthetic of most of Gates' work was something that happened serendipitously, he says, with his first project, The Archive House. He says: 'I'm proud to say that it was not a design decision at all... We got a call saying there was a farm being torn down in Indiana, we went and got the wood.

If there was enough wood to do the entire facade then we'd use it all. If we ran out seven-eighths of the way through then we'd put whatever clad was reasonable next to it. It's the same way Sanctum was built. We knew that there were buildings being dismantled and we were able to reach in and say hey, we'd love to have 5,000 bricks from the Salvation Army... Where traditionally architects would design the building first we were depending on the materials and the materials dictated what we could do... That was very exciting. That feels like an anti -- a complementary -- architecture. We just mined the city so that it would be reflected in the architecture.'

Whether his projects last five, 10, 20 years, and whether his example can inspire a whole new way of doing things, who knows. He's clearly having a blast demonstrating what's possible when you focus on what's desirable, and is bringing a growing number of communities along for the ride. That generosity, not forgetting the courage required to devise and build the antidote to sterile, top-down city planning, would be legacy enough for most people. Somehow you feel Gates has a whole lot more dreaming and doing up his sleeve.

Constructing Sanctum

Sanctum sits just inside the entrance to Temple Church, looking for all the world like a junkyard DIY ark has just crash-landed on to this venerable site. Badly bombed in the Second World War, and rarely opened to the public since, it took some persuading by Situations for English Heritage to let Theaster Gates and his architect/artist of choice Andrew Cross build on the remains - some of them dating back to the 12th century.

If the building's exterior references a makeshift boat, the interior is a friendly cross between a timber lodge and a twin tepee. Huge reclaimed joists create a dramatic and lopsided M-shaped ceiling that from the outside looks like the roof has partially collapsed and, from the inside, 'just bonkers from a structural engineering point of view' says Cross himself. But there is a method in this madness. Cross and Gates, whose shared hero Gordon Matta-Clark loved to carve up buildings and mess with the architectural orthodoxies of how a structure should look and feel, started out simply with the desire to put people at the centre of the design. They also had to design a building based on the materials that had been salvaged from around the city - bricks from the Salvation Army Citadel, timber joists from an old warehouse, doors from Bristol's Edwardian chocolate factory.

The focus for the design was on resonance - creating an acoustic that would work for a 40-piece choir or a single banjo - and intimacy. The smaller 'tepee' was deemed necessary, says Cross, so that 'if a performer wanted to go and hide in that space, or if as a participant or audience member you wanted to you could curl away in a corner... I was trying to create as many different elements of a building as possible but keep it as simple as possible, so when you walk in there's something so crazy going on you can't focus on any one thing unless it's a performer. It slowly reveals itself.'

Sanctum is the antidote to typical church architecture, says its architect. Photo Credit: Max McClure

There is no division between audience and musicians: the reclaimed wood strips that delineate the 'stage' run right from the entrance to the end windows. Without much in the way of ornament or embellishment, the interior feels robust, humble, welcoming. It's designed to accommodate a maximum audience of 50, but chairs are loosely arranged, free to be whisked away if desired, while ruined ancient-pillar remnants have been left where they are and transformed with a few planks into tables and benches.

Through a cluster of repurposed Georgian windows that form the back wall, the church ruins beyond are visible but not rendered particularly picturesque. It is not a structure that lends itself to endless visual documentation - viewed through a camera lens the flat window planes and rough planks against the church architecture appear nonsensical. Cross loves this and actively promotes it in his work: 'Jim Stephenson, who's my photographer of choice, gets really annoyed with me because I keep building these things that are really hard to photograph. I like that it communicates: "It's not worth the photograph; just enjoy what's in front of you".'

Sanctum is the antidote to typical church architecture, says Cross, which is all about making the audience feel humbled, overawed by the power and wealth of the church. With Sanctum, says Cross: 'You walk along the brick pathway and enter a massive door, and... you just feel so safe when you get in there. There's no "Last Chance Saloon" feeling being exposed.

That's part of the beautiful thing of what architecture and art and buildings can represent. It's something that's absolutely missing from our built environment, yet so easy to achieve.'