Dublin's most important medieval port has long since settled into its role as an elegant dormitory village, but there are some revealing vestiges of its illustrious past, most notably the remains of three of the eight castles that once lorded over the area. Facing each other on Castle St are the 15th-century Archibold's Castle and Goat Castle. The latter (aka the Towerhouse), along with the adjoining St Begnet's Church, has been converted into the Dalkey Castle & Heritage Centre, where models, displays and exhibitions are but the backdrop to the 'Medieval Experience', a live show every 30 minutes by actors from the Deilg Inis Living History Theatre.
Overlooking Bullock Harbour are the remains of Bulloch Castle, built by the monks of St Mary's Abbey in Dublin around 1150.
A few hundred metres offshore is Dalkey Island, home to St Begnet's Holy Well, the most important of Dalkey's so-called holy wells. This one is reputed to cure rheumatism, making the island a popular destination for tourists and the faithful alike. The island is easily accessible by boat from Coliemore Harbour; you can't book a boat, so just show up. The waters around the island are popular with scuba divers; qualified divers can rent gear in Dun Laoghaire, further north, from Ocean Divers.
To the south there are good views from the small park at Sorrento Point and from Killiney Hill. A number of rocky swimming pools are also found along the Dalkey coast.
About 1km south of Dalkey is the super-affluent seaside suburb of Killiney, home to some of Ireland's wealthiest people and a handful of celebrities, including Bono, Enya and filmmaker Neil Jordan. The attraction is self-evident, from the long, curving sandy beach of Killiney Bay (which 19th-century residents felt resembled Naples' Sorrento Bay, hence the Italian names of all the local roads) to the gorse-covered hills behind it, which make for a great walk. Alas, for most of us, Killiney will always remain a place to visit; on the rare occasion that a house comes on the market, it would take a cool €5 million to get the seller to bite.