Sillamäe (Estonian for 'Bridge Hill'; also known by the Germanised names of Sillamäggi or Sillamägi) is a town in Ida-Viru County in the northereastern part of Estonia, on the southern coast of the Gulf of Finland.

Among other famous vacationers of Sillamäggi were the poet Konstantin Balmont (1905), painter Albert Benois (1898 and 1899), physicist Paul Ehrenfest (1908–1912), botanist Andrei Famintsyn (1890s), historian Mikhail Gershenzon (1911–1914), inventor Boris Rosing (1902–1911), and composer Pyotr Ilyich Tchaikovsky (1868).

From 1927 to 1929, the Swedish company Estländska Oljeskifferkonsortiet built an oil shale processing plant and a power station at the location of Türsamäe Manor, on the western side of Sillamäe.

The German defensive positions on the hills east of Sillamäe, known as Sinimäed, formed the Tannenberg Line during the Battle of Narva.

In the following years, richer uranium ores were imported to the Sillamäe plant from various locations of Central Asia and the Eastern Bloc, mainly from mines in Czechoslovakia, East Germany, Hungary, Poland and Romania including the Bihor mine operated by Sovromcuarţ (one of the SovRoms operated jointly by the Soviet Union and Romania).

By the 1990s, the pond presented a serious ecological hazard due to leaching of radioactive and other harmful particulates and dissolved materials into the Baltic Sea.

During the Soviet regime in Estonia, Sillamäe remained a closed town due to the secrecy and security measures related to the uranium production activities at the local plant.

Among rare earth element products are lanthanum, cerium, praseodymium, neodymium and samarium-europium-gadolinium carbonates, oxides, metals, chloride and nitrate solutions.

A regular ferry service between Sillamäe and Kotka, Finland was inaugurated in 2006, but was forced to shut down in 2007 due to a low load factor.