About Penobscot Building Annex
The Penobscot Building Annex is a high-rise office tower in Detroit, Michigan, located on 144 West Congress Street which is physically connected to the Penobscot Building. It was built in 1913 and stands at 26 storeys tall, with three basement floors, and 23 above-ground floors. It is primarily used as an office building. It was designed in the Chicago School architectural style. The 23-story part of the Penobscot Block was built on Congress Street but is now connected to the Penobscot Building Tower.