Query: On what hill did construction of Lutyen's Bungalow Zone begin?
Context: In the south, land up to Safdarjung's Tomb was acquired in order to create what is today known as Lutyens' Bungalow Zone. Before construction could begin on the rocky ridge of Raisina Hill, a circular railway line around the Council House (now Parliament House), called the Imperial Delhi Railway, was built to transport construction material and workers for the next twenty years. The last stumbling block was the Agra-Delhi railway line that cut right through the site earmarked for the hexagonal All-India War Memorial (India Gate) and Kingsway (Rajpath), which was a problem because the Old Delhi Railway Station served the entire city at that time.