The Orkney islands are an archipelago starting just 10 miles off the north cost of Scotland. My flatmate and I decided to take a long weekend trip to the islands in the spring of 2007 and drove the 6hrs to John O'Groats (the most northerly town in the UK) to catch the small ferry to South Ronaldsay Island. From there, you can drive via causeways to the mainland (the islanders term for the largest island). We stayed in a bed and breakfast in Kirkwall and took day trips around the island as nothing is more than 40 minutes drive away.
Orkney is most famous for its neolithic settlements and monuments and we had an amazing time seeing them. Although the weather was gray, windy, and usually wet the sights are still incredible. Our first stop was at the Stones of Stenness and the Ring of Brodgar (the largest stone circle in Scotland covering nearly 100,000 square feet). We then visited several chambered cairns including Cuween, Unstan, and Wideford. The wonderful thing is that they are open to the public so you can go inside and look around. Cuween (3000BC) was our favorite as you had to crawl in through a tunnel less than a meter high and about 10 feet long and then enter the main chamber which is over 2 meter hight. There are four side chamber, two of which have additional small side chambers - all of which you can crawl into. Unfortunately, the flashlight outside the cairn had a dead battery so we had to explore using our mobile phones and camera flashes.
We also explored several brochs including the Broch of Gurness, which is one of the best preserved. Broch were built as living quarters which could also serve as fortifications in the Iron age. They were originally over 30 feet tall with walkways build into walls surrounding a central chamber. The central chamber had a fire pit and many small cells and "rooms."
Finally, we visited the Neolithic village of Skara Brae (3000BC) and the largest cairn Maeshowe. The village originally consisted of several houses all build to an identical design, a workshop, and covered walkways inbetween. Each house included two build in beds, a fire pit, and a cupboard (For a video tour of Skara Brae click here). The cairn Maeshowe is the largest in Orkney and dates from 2700 BC. It is estimated that it took over 100,000 man hours to build and consists of a 36 foot long entrance passage, a large central chamber which is over 13 feet tall, and three side chambers. It is most famous for its connection to the winder solstice when the winter sun shines down the long entrance tunnel and shines on the far wall of the cairn. Thanks to a web cam it is now possible to watch this occurance live from Nov 25th through Feb 5th (Solstice is on Dec 21-22). Maeshowe also contains numerous viking ruins (viking graffiti) saying things such as "Ingigerth is the most beautiful of all women" and "Haermund Hardaxe carved these runes."

Orkney lay athwart a great sea-way
from Viking times onward, and its lore
is crowded with sailors, merchants, adventurers,
pilgrims, smugglers, storms and sea-changes.
The shores are strewn with wreck, jetsam,
occasional treasure.
- Orcadian poet George Mackay Brown