Some believe that Stonehenge (2500 BCE) in England was built to help establish when the Summer Solstice occurred.
Males and Females sleep up to 18-20 hours a day in most cases. Depending on how hot or if the weather is perfect than the lion will sleep. If the weather is good ther will sleep about 14-18 hours and go hunting or playing.
2002a). Golden lion tamarins sleep as a group in hollow tree cavities or in dense vines and epiphytes. They prefer sites that are between 11 and 15 m (36.1 and 49.2 ft) off the ground and repeatedly use sites within their home range, but do not generally sleep in the same spot on consecutive nights (Kleiman et al.