The greatest shrine, but also the most difficult to reach

The correct answer is:

Jerusalem

Medieval christians believed that a pilgrimage to a holy shrine was a particular spiritual benefit. The greatest shrine but the most difficult to reach was The Holy City of Jerusalem. Some christians sought spiritual solace by traveling to the pilgrimage sites. Many went to local shrines honoring the Virgin Mary, but Jerusalem, Rome and Santiago de Compostela were the most desired locations.

the viking voyages took place during the middle ages, which was about this time. 500 to 1350. the viking voyages took place during the middle ages, which was about this time.