Atwater Holdings, a Pennsylvania-based company, plans to open a high-end cocktail lounge with outdoor dining next spring in the lobby of the historic Lafayette Building on the corner of Congress and Park streets.

The Sagamore Hill Lounge at 638 Congress St. will be located in a renovated portion of the existing lobby of the Lafayette, which has both apartments and shops.

The target opening date is April 1, according to its licensing application filed with the city.