1. Palvolgyi Caves, also known as Pálvölgyi Barlang in Hungarian, is a limestone cave system located in Budapest, Hungary. The caves were initially formed over millions of years by underground watercourses, and were later discovered by humans around 1904. The cave system is approximately 31 kilometers long, with only around 3 kilometers open to the public. Visitors can take guided tours of the caves, which include beautiful stalactites, stalagmites, and various other speleothems. There are also several underground chambers to explore, some of which are used for concerts and events. The caves are part of the Buda Thermal Karst region, which includes other cave systems in the area.

2. The working hours of the Palvolgyi Caves vary depending on the season. During the summer months (from April to September), the caves are open daily from 10 am to 4 pm. During the winter months (from October to March), the caves are open on weekends only from 10 am to 4 pm. The phone number for the caves is +36 30 868 32 68.

3. Tickets for the Palvolgyi Caves can be purchased on-site at the ticket office. The prices vary depending on the type of tour and the age of the visitor. There are three main types of tours available: the standard tour, the adventure tour, and the exclusive tour. The standard tour takes around an hour and costs 2,500 forints for adults (approximately $8.50 USD) and 2,000 forints for children. The adventure tour is a more challenging route that includes crawling and climbing, and costs 4,500 forints (approximately $15 USD) for adults and 3,500 forints for children. The exclusive tour is a private tour for groups of up to 10 people, and costs 28,000 forints (approximately $95 USD). The caves are located in the Pálvölgyi-Mátyáshegyi Nature Reserve, and can be reached by taking bus 65 or 65A from Széll Kálmán tér.