The landscapes of Gwynedd - the historic counties of Anglesey, Caernarfon and Merioneth - are the setting for many of Wales' greatest buildings. Beaumaris, Caernarfon, Conwy and Harlech castles are unsurpassed as works of medieval military architecture. Penrhyn is the epitome of romantic castle-making from the Regency age, while the bridges and viaducts constructed for Thomas Telford's new high road and Robert Stephenson's main-line railway are enduring wonders of nineteenth-century civil engineering. The Picturesque tradition makes a late and unexpected flowering at Portmeirion, the bewitching Italianate seaside village founded between the wars by the architect Clough Williams-Ellis. Prehistoric and Early Christian sites of immense evocative power are scattered through the mountainous interior, intermixed with a unique inheritance of early industrial monuments, including vast slate quarries and some celebrated narrow-gauge railways. The diverse towns include the planned Georgian settlement at Tremadoc and the ambitious seaside resort of Llandudno. Atmospheric medieval churches, prolific Nonconformist chapels and houses in distinctive vernacular traditions are plentiful throughout. Altogether, no area of Wales is more rewarding to the architectural traveler.