Tom and Judy wanted more than just a home for themselves and their two children. On a site of outstanding natural beauty in Buckinghamshire, they set out to build an ambitious house - a symphony of angles, glass walls and exposed steel, with a dramatic inverted roof. Tom made himself site manager and main contractor. He had no experience but he liked a challenge - and, after all, how difficult could it be?

Kevin McCloud catches up with a couple he met some years when they set about the task of converting a disused electricity substation in Sunderland into a four-bed family home

Kevin returns to Somerset to see Ed and Vicky and their off-grid cowshed conversion, which they turned into a home and a business space.

In 2015, Paul and Carol's plans to build a fortress-like home on the edge of the wild West Pennine Moors were thwarted when they ran out of money and time. Have they finally finished it?

In the longest revisit in Grand Designs history, Kevin McCloud returns to Devon to see if Sue and Martin's renovation of two ancient barns has finally come to fruition, two decades on.

Piers and Emma build the first new listed castle in the UK for 100 years, complete with a moat and futuristic tech. It's the biggest ever Grand Design, so is even their £2m budget enough?

Kevin revisits Tony and Sharon, who fell in love with a completely dilapidated Georgian home in London and undertook the challenging task of restoring it to its former glory

After 10 years of living in a small house in east London, John and Eleni hankered after modern, open-plan living. They didn't want to move, so they decided to give their Victorian terrace home a radical redesign. The house was in a conservation area, so the outside had to remain unchanged. Inside, however, they decided to rip out everything including walls, ceilings, floors and start again.

Paul and Penny are tearing down their million pound home in south London to build a contemporary mansion. But the challenge of building a complex home soon starts to bite.

Kevin McCloud is in lslington where Jeremy Till and Sarah Wigglesworth have come up with a highly experimental design for a home/office.

Kevin McCloud revisits an innovative housing scheme in Birmingham. Just over two years ago a group of 11 men and women agreed to build, not just their own, but each other's homes.

Kevin McCloud presents the first of four special programmes inspired by 15 years of Grand Designs. He begins with a look at the challenges of self-building in the city, where space is at a premium and architects have to be at their most ingenious. Kevin uses footage from the best urban builds from the show over the years, meets pioneers at the forefront of the latest architectural thinking and looks at clever innovations that continue to transform people's lives to reveal which designs work best and why.

After recovering from a life-threatening brain haemorrhage, Bram Vis, his wife Lisa and their two children want to build a house for sharing on a seaside plot on the Isle of Wight. Kevin McCloud follows the family's progress as they build an ambitious home complete with entertaining spaces and a swimming pool. However, the sheer scale of their project soon becomes clear when their original pounds 850k budget spirals out of control.

Deep-sea diver Adrian Corrigall and wife Megan want to build a concrete family home that Adrian hopes will prove the ultimate 21st-century country house.

With a plot of land in Sussex overlooking the South Downs, newly-weds Jane and Willem wanted a house that would be atmospheric and open to the countryside. Inspired by memories of America, Jane planned a New England-style gabled house with large windows to make the most of the views.

Graeme and Melanie want their new home in Hackney to celebrate their blended family. But squeezing the bright red-clad house onto their tiny garage plot proves a huge challenge.

Kevin travels back to Doncaster to catch up with self-builders Michael Hird and Lindsay Harwood and their futuristic glass and steel house in a suburb of Doncaster.

Hillcott Barn looked more like a Tuscan monastery than an English barn. When the farmer put it up for sale, most people who viewed it walked away. It was dark and isolated and could only be reached by a half mile farm track with a steep 1:8 gradient. But furniture designer Robert Ellis (58) had had his eye on it for some time. For years he’d been jogging past the barn and always thought one day he’d like to live there. Against all advice, Rob and his wife Jane, (58) a textile designer, went ahead and bought the barn for £210,000 and proposed to convert at £250,000.

In Maidstone, Jean and Bill Letley, a septuagenarian couple plan a highly contemporary bungalow complete with underfloor heating and prototype steel foundations. The project would test even the most accomplished workmen, but is left to their daughter and son-in-law, who have little building experience and have to make personal sacrifices.

Jonathan and Lindsay want to build a house that's exciting to look at, cheap to run, and ecologically sound. But the build is a battle, with technologies that don't work and a tight budget.

Kevin McCloud revisits Alan and Judith Dawson in west Cumbria, where they began constructing a prefabricated home in 2009. They employed a method of building that should have allowed them to assemble the home in just 15 days on a budget of £300,000, and the presenter returns to find out whether they were successful.

In Brixton in south London design-mad couple Mary Martin and Carl Turner want to build a home that resembles a giant stack of glass cubes that's a Zen retreat from the noise and chaos of the capital. Mary and Carl want to build something never seen before amongst Brixton's traditional Victorian terraces. Minimalism-obsessed Mary and her architect partner Carl have spent years renovating their homes to be as simple to live in as possible. But this project is bigger and more ambitious than anything they've taken on before. In order to save money, Carl decides he has to take on as many of the specialist build jobs as he can. The results are hair raising as the cranes and steel frames hit the narrow plot. But Carl's biggest test lies ahead, when it comes to finishing the minimalist interior. The tiniest error in the detailing could ruin all the blood, sweat and tears he's put into building this urban sanctuary.

Tony and Ara want to create a house of healing dedicated to health and wellbeing, on a beautiful woodland clearing near Henley-on-Thames. But the site is fraught with emotional landmines...

Kevin McCloud revisits the improbable Islington home of two architects who built their avant-garde north-east London house out of straw bales, springs, nappy cladding and silver tin

Louise and Milko wanted to build the home of a lifetime. Milko's job as a well-paid City banker meant they could think big, so Louise set up her own architectural practice and they bought a disused violin factory in the heart of London's Waterloo. The crumbling building was hemmed in on all sides and had no views, but Louise had a vision of a spectacular loft-style home that would combine stunning design with utter luxury