Unakan Road (Thai: ถนนอุณากรรณ) is a road in the Rattanakosin Island or Bangkok's old town zone. A short road that has a beginning at Unakan intersection, where it meets Charoen Krung and Burapha roads, opposite The Old Siam Plaza in Wang Burapha area. Then, it runs straight north in parallel with Wat Suthat and Siriphong road before ends at the corner of the Giant Swing, with a total distance is 446 m (1,463 ft).

It was built by royal command of King Mongkut (Rama IV) in memory of Prince Unakan Ananta Norajaya, his son born to consort Piam Sucharitakul (later Princess Piyamavadi), whose had a residence here. The young prince died, at the age of 17 in the year 1873. After he died, his mother donated an amount of 8,000 baht to build public utility for the benefit of traveling to the people. Department of Sanitation (currently known as Department of Public Works) therefore completed the construction of this road in 1900 and received the official name from the King Chulalongkorn (Rama V). In that era, it was considered a shortcut that bridges Charoen Krung and Bamrung Mueang roads.

In the early 20th century, the area around the road begin used to be a place to trade charcoal by rowing for sale in Khlong Lot Wat Ratchabophit, a branch of the old city moat, Khlong Khu Mueang Doem, that flows across the road. This area was therefore called Saphan Than (สะพานถ่าน, "charcoal bridge").

The territory of Saphan Than extends to nearby Ti Thong road, and covers three consecutive soi (alley)-like short streets were Soi Na Wang, Long Tha road and Soi Sa Song. The Prince's residence, known as Wang Saphan Than (วังสะพานถ่าน, "Saphan Than Palace"), was demolished and rebuilt into a two-story market named Bam Pen Bun since the pre-World War II era until the 1950s and 1960s that Wang Burapha reached its peak of prosperity. The market was also popular. In addition to being a wet market and selling various kinds of products as part of Wang Burapha commercial district. It was also a well-known place for prostitution.

As time passed around the 1970s, when the popularity of Wang Burapha declined. Bampen Bun Market was demolished and rebuilt into apartment named Bampenbun Flat and shophouses as seen today.

13°44′49.48″N 100°30′03.88″E / 13.7470778°N 100.5010778°E / 13.7470778; 100.5010778