The St. Louis office of Momentum Worldwide is moving its 150 employees from Richmond Heights to downtown west St. Louis.

The advertising agency has leased 27,850 square feet of office space at 1831 Chestnut Street across the street from St. Louis Union Station and will move in December.

“As we’re a company built on how the power of experience can improve brands, we’re very excited for a move that demonstrates how dedicated we are to our world class talent’s experience at our agency,” Momentum Worldwide's chairman and CEO Chris Weil said in a statement. “The growing energy and vibrancy of downtown St Louis is the perfect environment for us to create inspired, creative work that will continue to connect us and our clients with opportunities and people around the world.”

Momentum will occupy the seventh floor of the building and the space will undergo a multi-million dollar gut rehab, said John Warren, vice president at commercial real estate firm JLL, which represented the building's landlord, Oak Street Real Estate Capital, in the lease.

Momentum will have an exterior sign on the west side of the building and a private rooftop deck.