Totally leafless tree (well not quite if you take into account the few new ones close to the base...last photo) . Flowers remind me of the Barringtonia asiatica...Fish Poison tree but these are white.
Acharya Jagadish Chandra Bose Indian Botanic Garden previously known as Indian Botanic Garden is situated in Shibpur, Howrah near Kolkata, West Bengal, India. Most trees here do NOT bear name plaques.
Blooms are reportedly Rose coloured or white..evidently, this one has white blooms.