Morrison Construction invited Michael Russell, Cabinet Secretary for Education, to lay the final section of concrete on the first floor of the main teaching block.
He was joined at the ceremony by Councillor Paul Godzik, Education Convener for the City of Edinburgh Council, Paul McGirk, Chief Executive of Hub South East Scotland, the Council's development partner and Eddie Robertson, Regional Director of Morrison Construction.
The high school rebuild is part of the unique James Gillespie's Campus Project which will see new buildings being constructed across all aspects of the campus which serves pupils aged from 3 to 18 years in nursery, primary and high schools all on the same site.
Last year the first phase of the ambitious project was completed with the official opening of the new nursery; two new classrooms and a gym at James Gillespie's Primary School and the delivery of a new synthetic pitch at Thirlestane Road for the high school.
The high school project will see most of the existing buildings being replaced in two phases. The first phase started last October with the demolition of most of the existing buildings to allow the construction of new main teaching block to be progressed. This is now well underway and is scheduled to open in Easter 2015.
The final phase of works will see the delivery of the new sports and performance buildings with the project due for completion for the start of the 2016/17 school year. In addition, the A-listed Bruntsfield House at the centre of the campus is also undergoing a major refurbishment.
The high school replacement project has received significant Scottish Government funding through the ‘Scotland's Schools for the Future' programme which is managed by the Scottish Futures Trust. The project is being delivered by Hub South East Scotland with Morrison Construction having been appointed as the contractors.
Cllr Paul Godzik, Education Convener, said: "I'm delighted to see the progress that has been made on this project, and to welcome the Cabinet Secretary for Education Michael Russell to James Gillespie's.
"The site is really beginning to take shape now. When I opened the nursery last year I was hugely impressed by what was delivered and I know that pupils and staff are excited about the high school opening.
"This is a really unique project as it benefits children right from nursery age through to their high school years."
Cabinet Secretary for Education Michael Russell said: "The Scottish Government is committed to delivering good quality, well designed, sustainable schools through an investment of £1.25 billion in the Schools for the Future programme. I am pleased that we could contribute just over £20 million in funding for the construction of the new James Gillespie's High School which will provide state of the art accommodation for more than 1,000 pupils.
"I am delighted to help mark this milestone in the construction process which will result in a fantastic new school that the whole community can be proud of for many years to come and I look forward to seeing the new school in 2016."
Paul McGirk, Chief Executive of Hub South East Scotland, the City of Edinburgh Council's development partner, said: "We are excited about the progress being made with the construction of the high school. It's fantastic to start seeing the physical results of a great deal of collaborative work between ourselves and the City of Edinburgh Council.
"We look forward to continuing this successful partnership to deliver a modern, fit-for-purpose facility which will benefit both children and staff."
Morrison Construction's Regional Director, Eddie Robertson said: "The work is now at a significant stage with the completion of the structural steel frame of the new teaching block, which lets us proceed with all the other construction trades.
"When this is completed and occupied by the school in April 2015, we will enter the final phase, demolishing the last of the old buildings to create the space to build the sports and performing arts buildings and the sports pitches."
As a Hub development, the project is delivering a number of community benefits. It will support up to 250 jobs during construction, as well as six modern apprenticeships and a host of work experience opportunities. Already, more than 100 days of work placement have been undertaken, and there have been almost 3,000 visits by/to schools, colleges and universities in relation to the project.