Family-Owned
Built on Legacy
Founded in 1972
About One Horizon
One Horizon, initially founded as Torontario Mechanical and Electrical Contractors in 1970, transitioned to Horizon General Contractors in 1989, is more than a construction company. It is a family-built legacy—rooted in Toronto, shaped by decades of experience, and guided by a simple belief:
Buildings matter most when the people inside them matter first.
Our Beginning
The story of One Horizon spans decades, beginning in the early 1970s, when three brothers: Nick, Steve, and Larry Mirkopoulos, began their journey in Ontario’s construction industry. What started as a small family operation steadily evolved into one of the most respected names in institutional, municipal, and large-scale commercial construction across the province.
In 2025, Horizon General Contractors became One Horizon. A name that reflects what the company has always represented: one team, one standard, one reputation, and one promise to treat every project as if it carries the family name, because it does.
Our Work Across Ontario
Over the decades, One Horizon has delivered complex and impactful projects throughout Toronto and across the province, including:
Our portfolio reflects not only our technical capability, but long-standing trust earned through performance, accountability, and relationships that endure.
About our Founding President
Larry Mirkopoulos’ journey began on February 14, 1969, when he arrived in Toronto from his hometown in Greece.
Like many immigrants, he came with little more than determination, faith, and an unwavering work ethic. Over time, Larry became known not only as a builder, but as a leader defined by loyalty – to his family, his employees, and his community.
His philosophy is straightforward:
“Just invest time with your families. And really try to guide them to be good human beings. If you take that and you apply it in your business… then you are going to have a successful business.”
Larry frequently credits the tradespeople, engineers, subcontractors, and partners who helped shape One Horizon’s success. He believes construction is ultimately about serving others and helping convert people’s dreams to reality.
“We were fortunate to build a very efficient team of subcontractors, architects, engineers, and environmental experts.
Larry Mirkopoulos
Having a strong team is the best approach for successful outcomes.”
Community Is Part of the Foundation
From the beginning, One Horizon’s impact has extended beyond the job site, with philanthropy at its core.
The Mirkopoulos family has remained deeply involved in youth mentorship programs, charitable initiatives across Ontario and abroad, community development efforts, and local support organizations.
Giving back is not an afterthought.
It is part of the foundation on which the company was built.
“When you share the goodness of your heart, the rest falls into place.”
Larry Mirkopoulos
One Horizon Timeline
Early 1970s
Three brothers launch the family’s construction journey under the name Torontario Electrical Mechanical Limited.
1971
First office established at 111 King Street East, Toronto.
1973
Operations move to 275 Berkeley Street, expanding facilities and storage capacity.
1974–1975
Relocation to 319 Carlaw Avenue, marking a significant step forward in growth.
Late 1970s–1980s
Expansion into major municipal, provincial, and federal government projects across Metropolitan Toronto.
Key projects included:
- Toronto Pearson Airport (mechanical systems and elevator installations)
- Hospital mechanical retrofits and infrastructure upgrades
- CNE Grounds boiler and mechanical systems
- CN Tower solar installations
- CNR Railway Terminal Renovations
- Canada Post Offices
- de Havilland Canada – Downsview Solar Installation
- City of Toronto mechanical upgrades (including City Hall cooling systems)
- Environment Canada federal facilities
1988
Instrumental in the early development of Toronto’s film studio industry. Studio facilities were launched at Carlaw & Queen, supporting major international productions and contributing to Toronto’s emergence as a global film production hub.
Attended by Mayor of Toronto, June Rowlands, and other industry leaders, including Nick Mirkopoulos and Peter Lucas, the Leslieville / Riverside area became home to industry giants Cinespace Film Studios and Pinewood Studios, supporting major international productions and contributing to Toronto’s emergence as a global film production hub.
1989
Horizon General Contractors is formally established. The company transitions from trade contractor to full general contractor and developer.
Late 1990s–Early 2000s
Major redevelopment in Orillia: the historic Tudhope Building is converted into residential apartments, municipal facilities, and university space.
2000–2024
The developer behind the expansion of North America’s Film industry from the low millions to a multi-billion-dollar industry in Ontario alone, developing well over 1 million square feet of production studio and support space in Toronto and an additional 2 million square feet of production space in Chicago.
Continued delivery of landmark Ontario projects across healthcare, infrastructure, and institutional sectors.
2025
Horizon General Contractors officially becomes One Horizon, representing an integrated approach to construction, development, and long-term asset management—while continuing its multi-decade legacy.
Today
One Horizon operates as a multi-generational construction and development firm with deep community ties and a long-standing reputation across Ontario.
What We Stand For
What we build matters.
But what we stand for matters more.
These principles guide how we show up on every site, with every partner, and at every handoff.
Family Values and Togetherness
Every project carries the family name. That standard does not change.
People Behind Every Project
Construction is never just drawings and deadlines. It is the people behind the work who define its success.
Quality Without Compromise
Unquestionable performance is built through consistency, not convenience.
One Horizon Today
Today, One Horizon operates as a multi-generational construction firm supported by a strong professional team of engineers, consultants, tradespeople, and project leaders.
With decades of proven experience and deep roots, the company remains committed to:
Because the goal has never been simply to build structures. The goal has always been to build something that develops a lasting impact in the community.
Partnership
& Media Contact
For partnership opportunities, media inquiries, or collaboration requests, please contact our team directly.
