Although the constructions show different levels of architecture, the religious buildings exhibit a high degree of perfection. The construction was generally in stone and the roofs were built of tree trunks and thatched with ichu or straw. The walls lean slightly inward to protect against earthquakes. From the peak of the Huayna Picchu, situated opposite Machu Picchu, there is a panoramic view of the imposing spread of ruins and the Urubamba Valley. The breathtaking views from this mountaintop citadel and its well-preserved ruins are a photographer's dream. The subtropical climate means generally mild weather: the average year-round temperature during the day is 16ºC (60ºF). There are two distinct seasons - the rainy season is from November to March and brings heavy rains. Visitors are advised to dress accordingly during this season. The dry season from April to October brings higher temperatures.