Tepe Hissar (also spelled Tappeh Hesār) is an ancient Near Eastern archaeological site in Semnan Province in northeastern Iran about 360 kilometers east of modern Tehran.

The quantity and elaborateness of its excavated artifacts and funerary customs position the site prominently as a cultural bridge between Mesopotamia and Central Asia.

A small hillock on the east edge of the main mound was designated Treasure Hill after two very rich Strata IIIC buried hoards were found there.

[4] In 1925 Ernst Herzfeld examined the site as part of a regional survey, recommended it for excavations, and also noted the looting.

[11][1][12] A one-week surface survey for lithic (stone) finds was carried out by a team led by Giuseppe Tucci with the Italian Archaeological Mission in Iran in 1972.

[13] In 1976 a two month long re-study project was performed, utilizing modern methods of stratigraphic assessments, ceramic typological analysis and radiocarbon dating led by Robert H. Dyson and Maurizio Tosi for the University of Pennsylvania Museum, the University of Turin and Iran Center for Archaeological Research.

The study included a cleaning and replaning of the Strata IIB Burned Building, finding an additional room and hearth and showing the "tower" of the excavators was actually a buttress.

A geomorphological survey found that Tepe Hissar was settled on a natural hill that was next to a river that now flows further to the east.

[14][15] In 1995, a rescue excavation, due to an earlier rail line being run through the center of the site, was conducted by Esmaiil Yaghmaii, followed by areal soundings in 2006.

Results were:[22] Further confusing the matter, the 1976 excavators kept Schmidt's strata for burials but invented a new set of construction and occupation "stages" (A, B, C1, C2, D1, D2, D3, E1, E2, E3, F1, F2, and F3) in reverse chronological order.

In the second period (Hissar IIA and IIB), dated to the 4th millennium BC and the beginning of the 3rd, the burnished grey ware becomes predominant and the large number of lapis lazuli beads and alabaster finds, as well as the evidence of large-scale production of copper-based alloys and lead-silver, suggests that the site was playing a very important role in the trade and export of metal artifacts and semi-precious stones from the Middle Asia quarries to Mesopotamia and Egypt.

The third period of development (Hissar IIIA, IIIB and IIIC, chronologically attributed to the second half of the 3rd millennium BC and the beginning of the 2nd (Bronze Age), can be described as a proto-urban phase, mainly characterized by increased wealth, demographic concentration, mass production of plain ware and the construction of large public and ceremonial buildings.