Tvrđa's military importance decreased after the Berlin Congress of 1878 as a result of increasing political and military stability in the region. Two north-western bastions were demolished in the 1870s, making way for Ambrose's Park (). Construction of the "Royal Grammar School" started in 1881, and the "Royal General Secondary School" was completed in 1890. Episcopal seminary was also built in the south-western corner of the main square in 1898. These were the only buildings erected within Tvrđa walls in the last three decades of the 19th century.