sentences:  Originally built and operated by the City of Birmingham, the buildings were part of a stock transfer from Birmingham local authority to Optima Community Association in 1999, and today the buildings are owned by Citizen housing association (itself an amalgamation of several West Midlands housing associations).The Sentinels were the tallest purely residential tower blocks in the city until the completion of the 102 metre tall skyscraper Bank Tower 2 in 2019.They are also surpassed by the 122 metre tall newer Radisson Blu directly across Holloway Circus Queensway with 40 floors but this incorporates a hotel as residences.