The high temperatures during the day discourage many from visiting the site, said Phan Thanh Hai, director of the Centre. It currently opens for just one week every two years during the Hue Festival.
Hue was the seat of the Nguyen Dynasty from 1802 until the end of feudal Vietnam in 1945 and many domestic tourists find the former palace and tombs an interesting place to visit with the kids for a holiday.
Hue is normally 40 degrees Celsius (104 degrees Fahrenheit) during the daytime between April and September.
Ticket prices are US$5.45 (VND120,000) for domestic tourists and US$6.81 (VND150,000) for foreigners.