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Listed buildings and structures are officially designated as being of special architectural, historical or cultural significance. There are over half a million listed structures in the United Kingdom.
Listed status is more commonly associated with buildings or groups of buildings, however it can cover many other structures, including bridges, headstones, steps, ponds, monuments, walls, phone boxes, wrecks, parks, and heritage sites.

There are three main listing designations;
Grade I (2.5%) - exceptional interest, sometimes considered to be internationally important.
Grade II* (5.5%) - particularly important buildings of more than special interest.
Grade II (92%) - nationally important and of special interest.

There are also locally listed structures using A, B and C designations.

…read more at wikipedia Link

Almshouses are charitable housing provided to enable people (typically elderly people who can no longer work to earn enough to pay rent) to live in a particular community. They are often targeted at the poor of a locality, at those from certain forms of previous employment, or their widows, and are generally maintained by a charity or the trustees of a bequest.
Alms are, money or services donated to support the poor and indigent. Almshouses were established from the 10th century in Britain, to provide a place of residence for poor, old and distressed folk. The first recorded almshouse was founded in York by King Athelstan; the oldest still in existence is the Hospital of St. Cross in Winchester, dating to about 1132. In the Middle Ages, the majority of European hospitals functioned as almshouses.
An incomplete list of British Almshouses can be found at Link