“The basic structure of a Chorten consist of a square foundation symbolizing the earth, a dome symbolizing water, and thirteen tapering steps of enlightenment symbolizing the element of fire. These steps lead to a stylized parasol, the symbol of wind, which is topped in the ethereal sphere by the well-known ‘twin-symbol’ uniting sun and moon, which is the shimmering crown of the Chorten.”

-Courtesy buddhanet.net

Chorten (Tibetan) or Stupa (Hindi) meaning heap.

There are eight different kind stupas, all referring to major events in Buddha Shakyamuni’s life.

Lotus Blossom Stupa

Also known as stupa of heaped lotuses or birth of the Sugata stupa.

This stupa refers to the birth of the Buddha. It is said that “at birth Buddha took seven steps in each of the four direction”[3] (East, South, West and North). In each direction lotuses sprang, symbolizing the Four Immeasurables; love, compassion, joy and equanimity. The four steps of the basis of this stupa is circular, and it is decorated with lotus-petal design. Some times seven heaped lotus steps are constructed referring to the seven first steps of the Buddha.

Enlightenment stupa

Also known as the stupa of the conquest of Mara.

This stupa symbolizes the time the 35-year-old Buddha reached enlightenment under the bodhi tree in Bodh Gaya. It is said that he conquered worldly temptations and attacks Manifesting itself in the form of Mara.

Stupa of many doors or gates

After reaching enlightenment, the Buddha taught his first students in a deer-park near Sarnath. Here he gave his first basic teachings, with series of doors on each sides of the steps . The teachings are called the “Four Noble Truths, the six perfections, the Noble Eight folded Path and the twelve links in the chain of dependent origination.”

Stupa of descent from the god realm

42 years old, Buddha spent a summer retreat in Tushita Heaven, where his mother had taken rebirth. In order to repay her kindness he taught the dharma to her reincarnation. Local inhabitants build a stupa like this in Sankasya in order to commemorate this event. The stupa is characterized by having a central projection at each side containing a triple ladder.

Stupa of great Miracles

Also known as stupa of conquest of tirthikas This stupa refers to various miracles performed by the Buddha when he was 50 years old. Legend tells he overpowered several demons known as maras and tirthikas. This stupa was raised by the Lichave tribe to commemorate the event.

Stupa of reconciliation

The Sangha had been divided into disputing fractions. However Buddha managed to reunite the Sangha, and a stupa in this design was build in the kingdom of Magadha. It has four octagonal steps with equal sides.

Stupa of complete victory

This commemorate Buddha successfully prolonging his life by three months. It has only three steps, which are circular and unadorned.

Stupa of Nirvana

This stupa refers to the death of the Buddha, when he was 80 years old. It symbolizes the Buddha’s complete absorption into the highest state of mind. It is bell-shaped and usually not ornamented.

-Courtesy Wikipedia.com