He has researched McCulloch clan history, traced his roots to the McCulloch of Cardoness branch and unpicked stories of clan rivalries and lawlessness, all while overlooked by the framed 1750 map of Galloway hangs above his desk.
For him, all roads lead from Texas to Gatehouse of Fleet and Cardoness Castle, a six-storey tower built in the 15th century with walls that are 2.5 metres thick.
To stand in its shadow should have been a powerful moment to connect with his family's roots.
Around 15% of HES buildings are either closed or partly closed due to assessments and repairs (Image: Doug McCullough)
Instead, when he finally arrived at its doorstep, he was met with fences, no entry signs and padlocked gates.
"We had just been to Sweetheart Abbey but couldn't take pictures there without all the temporary chain fences in the way; clearly the fences are not that temporary," he recalls.
"That was bad enough.
"But Cardoness Castle is up a hill and there's a fence at the parking lot.
"We couldn't go from there without jumping over the fence, so we had to just look up at it from a distance and from behind the chain fences.
Fences and padlocked gates prevented American tourist Doug McCullough from visiting Cardoness Castle (Image: Doug McCullough)
"That was frustrating," he adds. "It's one of the most intact McCulloch properties and yet we couldn't even get up to it."
The visit in 2022 was such a let-down that when he planned a return visit to Scotland this summer, he left the very area where he has the strongest family ties off his schedule.
Doug McCullough and his family travelled from Texas to visit historic sites linked to his family (Image: Doug McCullough)
Instead, he took a week out and visited Ireland.
"We chose not to go to Galloway because of the frustrations we'd had there, even though that's where my ancestors came from," he says.
"I have all these reasons to go there but then there's this disappointment that I can't see the sites."
Scaffolding, metal barriers, chain fences and 'no go' zones have become part of the scenery for visitors to dozens of Scotland's historic sites, blighting treasured photographs and in some cases putting off visitors before they even bother to pack their bags.
Around 15% of Historic Environment Scotland sites are either closed to visitors or only partly accessible due to ongoing conservation works, masonry inspections or concerns over stonework.
St Ninian's Chapel at Whithorn is 'open' but has scaffolding around it (Image: Doug McCullough)
Historic Environment Scotland says 95% of the estate it manages is accessible, and that a programme of masonry inspections started in 2022 will be complete by Easter 2026.
But with the agency already grappling with a £842 million repair and retrofitting bill, there are fears the unsightly fences and no entry signs may be in place for months - even years - to come.
At the same time, the agency's management has come under scrutiny following allegations about senior staff behaviour, with investigations into misuse of hospitality and inappropriate conduct at an Edinburgh Castle event in 2023.
The turmoil within the organisation, which receives £74 million a year to look after more than 300 historic sites, has reportedly left some of its 1,600 employees "stressed, upset and angry."
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While for its collection of treasured buildings, their future hinges on a HES assessment of how they can be managed in the face of climate change, rising visitor numbers and a shortage of traditional building skills.
It has previously warned that an approach of "managed decay" may be applied to some particularly troubled sites.
For tourists, though, any behind-the-scenes crisis is secondary to the sight of locked gates and warning signs at properties they've dreamt of visiting.
And, for tour guides and businesses - particularly in off-the-beaten track areas away from the 'headline' destinations of Edinburgh, Stirling and favourite castles in the Highlands - there is mounting concern over the long term impacts.
In Dumfries and Galloway, where eight key sites out of the 30 in the care of HES are either closed or have restricted access and where others have been shrouded in scaffolding for years, some wonder whether other 'popular' locations have been prioritised for masonry inspections and repairs.
There, Threave Castle is off limits due to masonry inspections, along with Cardoness Castle, Lochmaben Castle and St Ninian's Cave.
Caerlaverock Castle near Dumfries, which is open but has some areas closed to the public (Image: Damian Shields/ VisitScotland)
Access is restricted at Caerlaverock Castle and Sweetheart Abbey - where fences and scaffolding have been in place for several years - and at Carsluith Castle and Glenluce Abbey.
Mark Donald, who runs Dumfries Tours, says working around closures and restricted access has become "a bit of a chore" and is impacting international visitors who often plan trips several years in advance.
"I have a couple from the States who are McCullochs and who want to renew their vows at Cardoness Castle for their 30th wedding anniversary," he says.
"I have a celebrant and a piper lined up and a tour itinerary mapped out.
"However, HES have informed me the castle is unlikely to be open in 2026.
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"This was to be part of seven-day tour of Dumfries and Galloway, but it looks like they are not coming now.
"That's business lost for me, but more significantly this couple have lost an opportunity to make lasting memories of their time in Scotland. It's such a shame."At MacLellan Castle in Kirkcudbright, scaffolding that's been in place for at least six years, has placed plans for a Clan MacLellan gathering next year into jeopardy.
The gathering had potential to bring hundreds of American tourists to the area but was halted after the organisers, Kirkcudbright Summer Festivities, said uncertainty over whether the castle would be open had made it "impossible to plan".
In North America, Clan Johnston/e president Paul Johnston is organising a trip for around 50 members to Dumfries in May 2027. The group's itinerary includes Caerlaverock Castle which currently has some restrictions in place over where visitors can enter.
"I can respect having areas of old structures closed off where they pose a safety hazard," he says.
"But I'd not appreciate barriers blocking sightlines."
Tourists visiting Sweetheart Abbey pose with scaffolding and fences in the background (Image: Mark Donald, Dumfries Tours)
Tour guide specialist Mike Peddie's business, Secret Scotland, compiles custom curated and off the shelf tour itineraries for visitors.
He says some historic sites are so blighted by fencing and out of bounds areas that "they're not worth making the trip for".
"HES appear to have prioritised the reopening of attractions based on popularity and tourist demand," he says.
Many visitors may not even realise the scale of the issue: "People who live near the attractions probably notice the closures far more than the majority of overseas visitors do, as they aren't on their bucket list - a symptom of the 'Outlander' effect.
"We discuss with clients what motivates them to visit a certain place and if it is closed or unavailable, we suggest alternatives that deliver the same or better experience."
Sweetheart Abbey at New Abbey, Dumfries, where scaffolding has been in place for several years (Image: Doug McCullough)
Yet for some, no alternative will do.
Rodney McCulloh of Ladoga, Indiana, runs McCullohReunion, a website devoted to telling the clan story and connecting people who share the McCullogh name and its variations.
He has visited ancestral sites on four occasions since 2010 and often left questioning how some buildings embedded in Scottish history could fall into complete dereliction.
odney McCulloch was able to enter Cardoness Castle during a previous visit (Image: Rodney McCulloch)
"We were thrilled to find and tour Cardoness Castle as well as seeing Barholm Castle, Myrton Castle and Green Tower Motte & Bailey," he says of his first visit.
"This past year we returned again and found the remains of Killaser Castle which we had missed on our earlier trips.
"It now only consists of a few courses of stones, the remnants of the lower wall sections, slowly crumbling and sinking into the small motte it rests on.
"It has been in this condition for well over a century and though beyond restoring, it is a shame to see it disappearing with apparently no protection by anyone or anything.
American tourist Doug McCullough's holiday snaps of Ninian's Chapel showed an array of metal fences (Image: Doug McCullough)
"Myrton is another sad monument to the destruction permitted to be inflicted on these priceless buildings.
"Like Killaser, it is being permitted to slowly crumble and sink into the small motte it rests on.
"How are such treasures with such deep history permitted to crumble and disappear like this?"
He first heard of Cardoness Castle from his grandfather - making his first visit there particularly poignant.
"I climbed the stone spiral stairs six storeys up to the top... it was an exhilarating experience, and one grandpa would have treasured," he says.
Rodney McCulloch during a visit to Cardoness Castle before it closed for structural reasons (Image: Rodney McCulloch)
"When we returned to Galloway this past year, we were disappointed to find the castle still closed for masonry inspections.
"How long does it take to do an inspection?
"It has been closed now for several years and others of my relatives have also been disappointed to make the journey but not have the pleasure of going through the castle.
"The castle has such a deep and fascinating history for everyone, not just the McCullohs."
Scaffolding has been in place at Sweetheart Abbey for several years (Image: Doug McCullough)
At Dumfries Tours, Mark stresses the South of Scotland has plenty to ensure clients leave delighted to have experienced the area.
But, he believes the closures are hitting the area disproportionately hard.
"At least Caeverlock Castle, which is a big draw for visitors, is partially open and visitors can get photos from a certain angle without lots of scaffolding," he says.
"But at Sweetheart Abbey, which a lot of people want to see, the scaffolding has been up for years and you're never sure if it's going to be open or partially open.
"Sometimes you see stone masons working and think there's progress, then they disappear again and nothing happens for months.
Tourists' holiday snaps at some Scottish sites are being blighted by scaffolding and fences (Image: Mark Donald)
"It does feel like our region has been particularly hard hit and there's an apparent lack of urgency to change the situation.
"People understand if it's a safety issue, but there are whole areas that are no go zones," he continues.
"Is it all in danger of collapse or is it just HES being massively over-cautious?
"Climate change gets mentioned too. No-one's downplaying that, but it sometimes feels like a handy excuse for what is happening.
"Visitors still have a great time, and this is a fantastic area. But, it would be nice to see some progress being made."
A spokesperson for Historic Environment Scotland said: "We are fully aware of the importance of our sites to visitors and the local communities in Dumfries and Galloway, and we are committed to offering the best and most accessible visitor experience possible.
"While there are a number of sites in the region where visitor access is still restricted, we are continuing to make good progress with our programme of inspections and implementation of measures to enable reopening or increased access at these sites."
They added that Sweetheart Abbey is now closed for winter. The nave and cloister reopened during summer, while a major conservation programme is ongoing at the Crossing Tower.
At Cardoness Castle, it's hoped some visitor access will be possible season: "Our rope access team have recently completed localised masonry repairs at wall head level, and there is no scaffolding currently in place on site," they added.
St Ninian's Chapel is currently fully open, and while Caerlaverock Castle is open there are some access restrictions for conservation work and masonry inspections.
Meanwhile, the grounds and exterior of Carsluith Castle are currently accessible to visitors, and options are being explored to enable interior access, and at Glenluce Abbey, currently closed for the winter, there is visitor access to the exterior and grounds.
HES said it is "engaging positively" with Kirkcudbright Summer Festivities regarding Clan MacLellan gathering at MacLellan's Castle, where a major masonry conservation project is ongoing.
Now closed for winter, some internal access was reinstated earlier this year. HES said it is aiming for further reopening next season.
They added: "We have also recently completed an internal masonry inspection at Threave Castle and are finalising major repairs to the jetties on site, which will enable visitor access to the castle interior to resume in the 2026 season."