Question: John Still was a British archaeologist known for his discoveries at an ancient rock fortress located in what country?

Context articles: Sigiriya
Belogradchik Fortress
John Still (author)
Charles A. Burney
Peter J. Reynolds
David H. Trump
Audrey Henshall
John Myres
Tuancheng Fortress
Christopher Tilley

Sigiriya or Sinhagiri ("Lion Rock" Sinhalese: සීගිරිය , Tamil: சிகிரியா , pronounced see-gi-ri-yə) is an ancient rock fortress located in the northern Matale District near the town of Dambulla in the Central Province, Sri Lanka.
 The name refers to a site of historical and archaeological significance that is dominated by a massive column of rock nearly 200 m high.
 According to the ancient Sri Lankan chronicle the Culavamsa, this site was selected by King Kasyapa (477 – 495 CE) for his new capital.
 He built his palace on the top of this rock and decorated its sides with colourful frescoes.
 On a small plateau about halfway up the side of this rock he built a gateway in the form of an enormous lion.
 The name of this place is derived from this structure —Sīhāgiri, the Lion Rock.
 The capital and the royal palace was abandoned after the king's death.
 It was used as a Buddhist monastery until the 14th century.
The Belogradchik Fortress (Bulgarian: Белоградчишка крепост , "Belogradchishka krepost"), also known as Kaleto (Калето, "the fortress" from Turkish "kale"), is an ancient fortress located on the north slopes of the Balkan Mountains, close to the northwestern Bulgarian town of Belogradchik and is the town's primary cultural and historical tourist attraction, drawing, together with the Belogradchik Rocks, the main flow of tourists into the region.
 It is one of the best-preserved strongholds in Bulgaria and a cultural monument of national importance.
John Still (1880–1941) was a British archaeologist and author, known for his discoveries at Sigiriya and his book "The Jungle Tide".
Charles Allen Burney (born 1930) is a British archaeologist known for his discovery of Urartian sites in Turkey in the 1950s and his excavations at Yanik Tepe, Tabriz, Iran from 1960 to 1962.
Peter John Reynolds (6 November 1939 – 26 September 2001) was a British archaeologist known for his research in experimental archaeology and the British Iron Age and for being recruited as the first director of Butser Ancient Farm, a working replica of an Iron Age farmstead in Hampshire.
David Hilary Trump (1931 – August 31, 2016) was a British archaeologist known for his work in the area of Maltese prehistory.
 In 1954, Trump helped John Davies Evans excavate at Ġgantija.
 He took part in the excavation of many important sites in Maltese prehistory, including the Skorba Temples and Xagħra Stone Circle .
 From 1958-1963, he was a curator at the National Museum of Archaeology, Malta.
 He retired in 1997.
 He was awarded the National Order of Merit by Malta in 2004.
Audrey Henshall OBE (born 1927) is a British archaeologist known for her work on Scottish chambered cairns, prehistoric pottery and early textiles, including clothing found preserved in peat bogs.
Sir John Linton Myres (3 July 1869 in Preston – 6 March 1954 in Oxford) was a British archaeologist who conducted excavations in Cyprus in 1904.
 He became the first Wykeham Professor of Ancient History, at the University of Oxford, in 1910, having been Gladstone Professor of Greek and Lecturer in Ancient Geography, University of Liverpool from 1907.
 He contributed to the British "Naval Intelligence Division Geographical Handbook Series" that was published during the Second World War, and to the noted 11th edition of the "Encyclopædia Britannica" (1910–1911).
 He highly influenced the British-Australian archaeologist Vere Gordon Childe.
The Tuancheng Fortress or Tuan Cheng Fortress (Chinese:  團城演武廳 ,  团城演武厅 ,  "Tuánchéng Yǎnwǔtīng",  "Round Wall Fortress") is a historic 18th-century fortress located near the Fragrant Hills in the Haidian District of Beijing, China.
 Today, the fortress is a national museum and is also known as the Tuancheng Exhibition Hall.
Chris Tilley is a British archaeologist known for his contributions to postprocessualist archaeological theory.
 He is currently a Professor of Anthropology and Archaeology at University College London.