The ongoing government shutdown has closed many federally operated tourist attractions in D.C. and throughout the country, but the one at President Donald Trump's D.C. hotel is an exception.

The historic clock tower in the Old Post Office building on Pennsylvania Avenue, home to the Trump International Hotel, remains open with National Park Service rangers operating the attraction, prompting questions from an ethics watchdog group, the Associated Press reports.

Citizens for Responsibility and Ethics in Washington filed a Freedom of Information Act request with the General Services Administration in search of an explanation for why the tower is open and how it remains funded, despite 800,000 federal workers going without pay and many important agencies being understaffed. The shutdown is five days from becoming the longest in U.S. history, and attractions from the Smithsonian museums in D.C. to National Parks across the country have been closed or understaffed.

The federal government leases the building to The Trump Organization, which opened a 263-room hotel in September 2016. The GSA told AP the clock tower remaining open was mandated by law and unrelated to the relationship with Trump's business.

Trump has not divested himself from his company, and this is not the first issue with his D.C. hotel that has led to ethical concerns. The attorneys general of D.C. and Maryland continue to move forward with a lawsuit against the president over foreign payments at the hotel, and a federal judge in September allowed them to begin issuing subpoenas. CREW also filed a lawsuit over foreign payments to the hotel in January 2017, but it was dismissed due to lack of standing.

The hotel has also been cited as a potential conflict of interest in Trump's apparent involvement in the decision to keep the FBI on the Hoover Building site one block away, a reversal that has sparked congressional outcry and an Inspector General investigation.