The Treasury has cancelled an event allowing the public to take a look round its historic offices after the security threat level was raised, but other departments have allowed visitors access.
Notable buildings across London unlock their doors to tourists once a year as part of Open House day to give people a chance to see areas they would normally be prevented from visiting.
After the Parsons Green terror attack, the security threat level was raised to critical, which means a further attack is feared to be imminent, prompting the Treasury to cancel its involvement in the event.
But other departments, including the Foreign Office, which boasts the most opulent premises in Whitehall, and the Department for International Development, based in the Old Admiralty building, continued to allow guests in.
The Metropolitan Police also said it was looking forward to greeting people who had booked to see New Scotland Yard, its new headquarters.