Location: N57° 3` 47.70", E24° 1` 36.54"
Mangaļsala is located on the Northern side of Riga near Daugava estuary in the sea in front of Daugavgrīva. It is about 4.2km long and up to 2.7km wide peninsula between Daugava initial river-bed Vecdaugava and the waters of Riga sea bay – it is a field of sea sand blown by the wind and silt brought by Daugava. An old fishermen village was also called Mangaļsala on the Southern part of the island. Mangaļsala was joined to Riga in 1960. The forts were built and transformed during a longer time. Germans, Swedes and also Russians had put their hands on construction of these forts. Because of the change of the Daugava estuary direction in 1765 a Comet fort was started to be built on Mangaļsala on the right coast of Daugava. A construction of several forts in Mangaļsala and Bolderāja was started in 1912. Two forts with 254mm cannons and six forts with 152mm cannons and three forts with 138mm cannons were built. Two cannons were installed in each fort. Mangaļsala fortification system consists of several parts and they are located in a relatively wide territory.
A memorial stones in honour of Alexander II and his dauphin Nicolas Alexandrovich visit in 1856 and 1860 are still preserved on the dam. The “Riga magazine” on 28th of May, 1856 about this event writes: “On 27th of May, 1856 his Highness Alexander II after the service at 12.30 went with the ship Riga-Luben to Dinaminde fortress to see the equipment of the fortress and the fortification (bulwark)...” The memorial stones were damaged during the 90ies of the 20th century and were immured in the Western bulwark during its reparation. There is also a memorial place on Mangaļsala for the revolutionary of 1905 who were shot in the sand hills in 1906 when the punishment expedition was savagely dealing with the members of revolution groups. Mangaļsala became a place of punishments. From the archives it is known that the people who were determined to death from the central prison were transferred by a ship over Daugava, shot at the daybreak and buried, but the sand hills were evened out.
The fort was destroyed during the WW I when the German sappers were retrieving. In 1925 the government offered the reconstruction of the Daugavgrīva fort, but the parliament did not support this project. Comet fort dam which is included in the fort system is the only hydro technical building which is preserved since the 18th century which has been built for the river bank regulation in Daugavgrīva whose main task was to regulate the water flow in Daugava and ship traffic in the port territory. Comet fort is a cultural monument of Europe territory but at the same time it is one of the 100 most neglected and threatened objects in Latvia.