Major spot to visit in Janakpur:

Janaki Temple
Janakpur has the Janaki Temple (Mandir in Nepali) which is dedicated to Goddess Sita, and also has a Ram and Sita Marriage Mandir (or also known as Ram and Sita Bibaha Mandir in Nepali) which is said to have been built in the spot where they got married. Marriage anniversary of Ram and Sita is observed every year here through a festival which is also observed throughout Nepal. In the Janakpur region, one of such festival is the enactment of the wedding ceremony, decorating temples and monuments, burning of oil-lamps surrounding the temple and other historical sites in the region. Throughout the festival there are dramas in theaters and in open streets remaking the marriage ceremony of Ram and Sita. According to Hindu, Ram and Sita took birth to free the earth from the cruelty and sins of the demon King Ravana (Ravan). To learn more about the Hindu Goddess, see web link at the end of this page.

Some more information related to Janakpur:

Mithila Culture and Janakpur
Mithila culture is found in the Terai region of Nepal such as the Janakpur region and also found all the way up to the Northern Bihar state of India. Legend has it that Janakpur was the capital of Goddess Sita's father the King Janak. And often Sita is known by many names such as Maithili, Janaki or Mythili. Mithila culture is rich with its own language known as Maithili, and with its own traditions, customs, arts and music. Many Mithila arts and paintings have historical and religious meanings, such arts are produced by many villagers specifically women's draw paintings having colorful and through provoking objects such as animals, Gods and Goddess on the walls of their homes.

About Ramayana
One of the greatest epic of all time is Ramayana, which is a a Hindu tale of God Ram and his wife Goddess Sita, their marriage, their struggle, sacrifice, and many facets of life. Ram marries Sita, then has to live for years in isolation from her before returning back to his royal palace. Sita is captured by Demon named Rawana. In the end, Sita disappears under the ground, and she is regarded as the Goddess of the Earth.