Lamu town has been designated a World Heritage site. Its buildings and architecture originate from the 17th century Arabs ''wintering'' in Lamu before sailing back in their dhows to Arabia on the trade winds with slaves, ivory, mangrove wood and spices. The houses they built are amazing. Built of coral rag bricks to a standard design; the rooms are always the width of a mangrove pole. They stretch back from an ornate doorway and around a central open courtyard. They have elaborate plasterwork on the walls and a sophisticated plumbing system. Many of the houses have been lovingly restored, mainly by wealthy Europeans. All the trades - builders, plasterers, furniture makers, are still easily available in Lamu. The town is a maze of narrow alleyways with a main 'street' running parallel to the sea front. There is a fort built by the Portugese and in Shela, an ancient mosque. There are ruins of an ancient settlement at Takwa, a short boat ride away.