@awnlee jawkingAs most anyone I too talk about my local experiences here in Latvia. Our landscape is predominantly flat with few rolling hills where almost any chance to look over the forest without climbing a structure bestow a landmark of a "mountain" (to be fair, the language doesn't differentiate between hill/mountain at all).
Direct ancestors of modern Latvians immigrated to the area no later than 7-9 century A.D. (when supposedly the ethnic warlike nobility arrived following the free peasants gradually settling in previously, possibly centuries before) slowly displacing and assimilating then indigenous finno-ugric tribes. Who exactly buried their VIPs in smalish artificial sand kurgans in that timeframe is often up to debate, but such, ~5-10 feet high ~15-20 feet diameter cones decorated by a lose ring of 12+ granite boulders around it's base can still be occasionally found and are believed to contain burials (that such a meager structure can at all be notable talks to the flatness and featurelesness of the land too). Build from fine sand, in some cases seemingly transported for significant distances many have likely be lost to opportunistic sand mining for various purposes throughout centuries.
Peasant homesteads naturally choose relative high ground, and nobles even more so, in particular, for defensive purposes (any homestead can easily be fortified to an extent, the traditional building plan considered such necessity) and often significant amounts of earthworks was invested to upgrade the natural features, either by steepening existing slopes, occasionally allegedly employing a river to do so, digging ditches across high ground, or in some cases possibly, or allegedly, building whole artificial hills to house hill forts. Or just as likely, open-air places of worship.
Stemming from the above mentioned tradition of burial kurgans or not at all, but the folksongs describing burial traditions, beyond-the-life beliefs, ancestral cult elements, or matters as trivial as orphan grief, have a "burial sand-hill" as a recurring element more often than not, often epitomized as dry, soft, and warm. While some of the best known ancient burial groups (of relative commoners) are in fact in valleys between such artificially modified hills, many historical and active examples of countryside cemeteries are indeed upon relative high ground or slope.
Founded even shortly before Germanic crusaders invaded in the early thirteen century, one of the very first (catholic) churches constructed was a massive stone masonry structure above a (dolomite) cliff on a river bank (the remains of it now can be seen on a low island in the hydroelectric plant lake).
Further churches were built as nodes of oppression of the occupation regime, often against significant resistance of the local population. As multiple legends tell it, "what builders build during the day, devil razed during the night" until a virgin maiden was sacrificed by walling her in alive, her wailing heard for days and weeks and... forever since, but the nightly destruction of the building site allegedly stopped with that. While virtually every countryside churches (and even greater majority of older city churches) each have this legend associated with them, only a few have proven archeological evidence such human sacrifice indeed could have taken place during their construction.
And yes, while obviously wooden Christian churches did happen both back then (especially for the orthodox branch seeping in from the east even before Catholicism arrived from west with "sword and fire") and later, the archetypal church is a heavy stone structure here, typically surprisingly freezingly cold inside.
Not only they were often deliberately placed upon previous sacred mounds or in some cases hillfort mounds (either deemed too small for crusader's own masonry castles, and/or only cleared of a hillfort later, long after the competing crusader's nest had been constructed nearby), to add insult to injury sacred stones were collected and split for their construction. There's an aside is necessary. Due to geology of the region, all and any granite or other "hard" stone pieces are imported by the ice shield from the Scandinavia across the sea. Thus, the rare boulders above certain size were seen as sacred by the pre-christian godkeeping tradition more often than not, and used to place them in intricate large scale patterns in and around the sacred mounds or groves, and/or possibly as property border marks, with or without runes or other markings.
While an alleged religious prohibition to use stone in construction before then is dubious at best, there's no surviving masonry examples prior Germanic invasion, when it suddenly becomes commonplace seemingly overnight, in both civil, military and (Christian) sacred architecture, and even peasant barns and cellars are often stone-build from then onward (yet still virtually never homes, granaries or saunas, except city houses (a category of buildings virtually non-existent upon then either) or much later, late nineteenth, twentieth century, and then being brickwork or poured light concrete, never stone, except rarely as facing tiling above framework, and then soft stone).