Great little "trulli" (kind of round cottages, with very few and very small windows). OK, don't expect luxury, these were initially modest village houses. The smallest bathroom/WC combo I ever saw in my life!
But it is definitely a unique experience. Very efficient, sympathetic and multilingual staff at the "take your keys and directions" spot.
For some funny reason this place is listed under "Bari" by Tripadvisor. While it is in Alberobello, about 40 miles southeast.
