Complex sentence: At the highest point of the hill is a 90-feet high (27m) Celtic cross erected as a monument to Francis Basset, 1st Baron de Dunstanville and Basset (1757--1835).
Split into simpler sentences: At the highest point of the hill there is a 90-foot high (27m) Celtic cross. This is a monument to Francis Basset, 1st Baron de Dunstanville and Basset (1757--1835).