Willmott Dixon has officially opened its new Sussex base.
The new office in Crawley expands the company's presence in the region.
The audience included company leaders and representatives from both Crawley and Surrey councils.
Russell Miller, Willmott Dixon's director for delivery in Sussex, said: "Willmott Dixon has been well established in the county since 1930 when we built Bailiffscourt at Climping near Littlehampton for Lord Moyne.
"Since then we’ve grown across Sussex and opening our new Gatwick hub, close to where many of our people live, is a natural evolution.
"Gatwick is a thriving area and has, along with Sussex, a really bright future with many bold and imaginative initiatives to encourage growth and investment.
"We want to be part of shaping that by basing ourselves in an area close to our partners and customers."
Cllr Peter Lamb, leader of Crawley Borough Council, added: "We're working hard, in partnership with private sector and public sector organisations, to ensure Crawley not only remains one of the best places in the region to do business, but keeps improving on that status.
"Willmott Dixon's decision to open an office in the town is a great testament to the impact of those efforts and their confidence in the future of Crawley's economy."