The magnificent capital of the Aztec Empire astonished even the Spanish Conquistadors.
Legendary geographical discoveries at the beginning of the Modern Age had not only redrawn maps, but also had a truly diverse impact.
The longest part of the digestive system, where most of the digestion and absorption takes place.
Connective tissues include loose and dense connective tissues, adipose tissue, blood, tendon and bone tissue.
The main parts of the human brain are the brain stem, the cerebellum, the diencephalon, and the cerebrum.
Taste receptors convert chemical stimuli into electric signals.
The main parts of the human brain are the brain stem, the cerebellum, the diencephalon, and the cerebrum, which is divided into lobes.
Olfactory receptors produce electric signals when stimulated by odours.
Rivers play an important role in shaping the Earth's surface: they cause erosion as well as carrying and depositing sediment.
Typical settlements of the Norsemen were not only established in Scandinavia, they appeared on distant areas as well.
The 'wise man' originated in Africa and dispersed throughout most of the continents.
The three types of muscle found in the human body are the smooth, the striated and the cardiac muscle.
This animation demonstrates the fine molecular structure and mechanism of muscles.
Neurons transmit electrical signals via chemical and electrical synapses.
The army of Alexander the Great successfully deployed siege towers in its attacks against fortifications.
A series of fortifications built to prevent incursions from northern nomadic groups.
The excellent road and aqueduct system covering the whole empire reflects well the development of the Roman civilisation.
The seminomadic lifestyle of the Bedouin adapted to the climatic and environmental conditions of the desert.
A type of large freshwater crayfish widespread in Europe.
Unicellular eukaryotes living in freshwaters, capable of feeding autotrophically and heterotrophically.