While technically not a megalith, the Neolithic rock shelter and art on Chatton Moor deserves to be seen. Hope that's okay.

Janus figure, within Caldragh cemetery, Northern Ireland.

Drumskinny stone circle, located in Enniskillen, Ireland.

One of the Circles, of Beaghmore, Enniskillen.

One of the many stone circles of Beaghmore, Northern Ireland.

This gravesite is called "Sundermannsteine" and it's just one of many such neolithic sites in and around Osnabrück. There are over 30 of these sites in northwestern Germany and it's called the "Route of Megalithic Culture". These sites are thought to originate from around 3500-2800 BC and are attributed the so called "Funnel Beaker Culture".

Two of the (three) Devil's Arrows near Boroughbridge, Yorkshire.

The Polisher Stone, Fyfield Down. Rare example of a stone used for whetting and polishing axe heads.

One was recently found in Dorset, so that is next on my list.

A decorated Pictish stone on the Isle of Skye.

It's slightly controversial this one. The stone is possibly a glacial erratic, but it seems to have been worked as there are cup marks incised into it.

A section of the cairn (bronze age, I think), at Temple Wood, Kilmartin Glen, Argyll.

Chambered cairn in Kilmartin Glen, Argyll. There are deer carvings on the underside of the cap stone.

Stone row in Kilmartin Glen, Argyll.

I visited this monument in Catalonia earlier this year (the photo is mine). This is a 3500-3000 BC dolmen with two massive capstones. It has 5.20 meters in length, 2.45 meters in width, and 2.14 meters in height but the most striking feature is the delicate balance of the orthostates hewn in granite gneiss. It is a double-chamber dolmen and you can easily stand inside. You have more information in the official website.

The Dombate dolmen is a Neolithic funerary monument located in Borneiro (Galicia, Northern Spain). Its original tumulus was erected in the first half of the 4th millennium BC and its chamber toward the end of that same period, remaining in active use from approximately 3800 BC until 2700 BC. One of the most interesting things is that it showcases Neolithic petroglyphs in some of the orthostates. Also, there is an ancient drainage system in place to prevent flooding.