This is a list of "twin towns" or "sister cities" in the continent of Europe — that is, pairs of local government

Local government

Local government refers collectively to administrative authorities over areas that are smaller than a state.The term is used to contrast with offices at nation-state level, which are referred to as the central government, national government, or federal government...

 entities in different countries which have town twinning

Town twinning

Twin towns and sister cities are two of many terms used to describe the cooperative agreements between towns, cities, and even counties in geographically and politically distinct areas to promote cultural and commercial ties.- Terminology :...

 arrangements. Where known, the date of formation of the twinning agreement is included in parentheses.

Note that the list is likely to always remain incomplete, since no canonical list of such arrangements exists; even those towns that are listed may well have arrangements which are not listed here.
However, a searchable, interactive list is maintained by Sister Cities International

Sister Cities International

Sister Cities International is a nonprofit citizen diplomacy network that creates and strengthens partnerships between United States and international communities. More than 2,000 cities, states and counties are partnered in 136 countries around the world...

. Note also that any twinning arrangement should be listed at two locations in the series of lists: once for each of the towns involved in the arrangement.