None have been found, but temporary tent-like structures are assumed to have been present at open-air camp sites of any duration, as must have been the case at Howburn (Ballin et al. 2010a), and there is likely to have been use of any suitably available rock-shelters and caves, as at Kilmelfort (Saville and Ballin 2009).
The evidence for the, admittedly rather ephemeral, structural remains known prior to 2000 was listed and discussed by Wickham-Jones (2004). It comprised a variety of stone, posthole, and stakehole settings, hearths, depressions, and other vague traces inferred from charcoal and artefact spreads, though there was also the suggestion of a circular post-built structure having been found at Nether Mills, Aberdeenshire, which has not yet been published fully (Kenworthy 1981) . Since then it has become clear that some much more substantial hut-like structures with sunken floors were being constructed by Mesolithic people (Waddington 2007), and a Scottish example has been excavated at East Barns in East Lothian (Gooder 2007; Gooder & Hatherley 2003). The large circular pit at Staosnaig, Colonsay, may also have been the base for a hut (Mithen 2000, 432), and possible further round huts are reported from Elgin (Suddaby 2007). Mesolithic people also appear to have dug pits for various purposes, some of which may be associated with above-ground structures for which no evidence survives (Murray et al. 2009).