One of the schools in Wrexham's secondary education reorganisation project, which cost £10m above estimates, has opened for the first day of term.
The 'super-school' at Rhosnesni follows a merger with other schools
Rhosnesni High School is the first of the two so-called "super schools" to be completed.
Pupils at Ysgol Clywedog are being taught at the old Groves school until building work is completed.
It is on schedule to reopen after the Christmas holiday.
Under the plan. the former St David's, Groves and Bryn Offa schools are closing and pupils will be taught at the rebuilt Rhosnesni and Ysgol Clywedog (the old Bryn Offa) sites.
The project is costing £22.5m, after the original estimate had been £12m.
But Wrexham council leader Neil Rogers said: "There was an underestimate certainly, not an overspend.
"We're on target and it's a real achievement for everyone who's been involved in the project."
He added: "Although there have been some setbacks along the way I believe that this project represents value for money and a new era for secondary education in Wrexham."
Mr Rogers said the type of facilities available at Ysgol Rhosnesni would help pupils achieve.
Early construction work at Ysgol Clywedog, which will be ready by Christmas
He said: "The council has recognised there are attainment targets that we've got to improve.
"On the funding arrangements Wrexham is 20th out of 22, that can't be allowed to happen. Wrexham council has made education a top priority."
The new facilities at Rhosnesni include computer suites, technology rooms, newly refurbished sports halls and improved outdoor sports provision.
Headteacher Bernard Knowles said: "Contractors and staff have been working hard to ensure that the school is ready for today's lessons.
"We are delighted with the facilities that we have and I am convinced that they will provide a solid foundation to take the school forward.
"With the support of staff, governors, parents and pupils Rhosnesni High School can now go from strength to strength and look forward to a very bright future."