North of Smolenice is the village Buková with water reservoir and a marked route, which leads southward to the romantic ruins of the Castle Ostrý Kameň from the 13th century. The Castle was a royal border fort guarding the Czech road in the past.
It is in decay since the 18th century though part of its walls, bastion, and adjacent buildings are still observable. The top of the Castle provides a nice view of the Malé Karpaty Mts. and the Záhorská nížina lowland.
Access: on foot from the water reservoir following the yellow hiking marks: Switch to red marking beyond the tourist cottage Brezinka (it takes about 45 min.); option to continue to the chateau of Smolenice or Castle Červený Kameň.