Alexander Castle was built around 1879 by Maharaja Suryakanta Acharya Chowdhury of Muktagacha, the same zamindar behind Shashi Lodge, and named, most accounts say, after the district magistrate of the time. So much of it was made of iron that people called it the Lohar Kuthi, the iron house.
It served as the Maharaja's guest house. Rabindranath Tagore stayed here for four days in 1926, and Lord Curzon was among the other guests. In 1948 the Teachers' Training College was set up in its grounds, and the castle became the college library.
It has been a protected monument since 1989, but the upper floor is in poor repair and closed. It stands on a working college campus, so visit respectfully and see it from the grounds.