These are very impressive and well worth the trip from downtown budapest. Easy to get to if you use the tube service then follow the signs. English friendly and inexpensive. I'd reccomend taking flip-flops as the changing rooms didnt seem that clean and the ground outside was fairly uncomfortable to walk on. There are many many saunas of varying temperatures, plunge pools, cold showers, steam rooms, rapid pools, a swimming pool, various smaller hot baths, two main outdoor thermal baths. A must visit. We also went to Gellert baths but this was far better. You can also combine a visit with a trip to the Zoo