East of the Lahn, you can walk up Blitzweg (served by bus 8) and a forest trail to the 36m sandstone Kaiser-Wilhelm-Turm , an outlook tower erected on Marburg's highest point in 1890. Thanks to a 'Lichtkunstprojekt' (light-art-project) inaugurated in 2007, at night you can turn a romantic neon heart on the exterior, visible all over town, by phoning [tel] 09005-771 207 (costs per minute €0.49 from a landline, €0.79 to €2 from a mobile; proceeds go to charity). The phone number and the artwork's name, Siebensiebenzwölf- nullsieben, refer to St Elisabeth's birthday on 7 July 1207.
