1. Citadella is a fortress located on top of Gellért Hill in Budapest, Hungary. It was built in 1851 by the Habsburgs as a strategic defense fortification. The fortress played a significant role in the Hungarian Revolution of 1848-1849 and was used for military purposes until World War II. Today, Citadella is a popular tourist attraction and offers stunning views of the city from its vantage point. Visitors can explore the fortress walls and its various historic monuments, including the Liberty Statue.

2. Citadella is open daily from 10am to 6pm. The phone number for inquiries is +36 20 585 7881.

3. Admission to Citadella is free, and visitors can access it by foot or via the Hop-on-Hop-off bus service. Additionally, the site can be reached by public transport, including tram 19 and bus 27 from the city center. The nearest metro station is Szent Gellért tér on Line 4 (Green Line).