It has retained some traces of its medieval appearance, especially the main gateway, beneath a watch tower, and reached by a bridge over the old moat.

About half an hour distant to the north-east, on the hillside, is the site of the famous Battle of Sempach (9 July 1386), in which the Swiss defeated the Austrians, whose leader, Duke Leopold, lost his life.

The spot is now marked by an ancient and picturesque Battle Chapel (restored in 1886) and by a modern monument to Winkelried.

It was the first document signed by all eight (plus Solothurn), but it also defined that none of them was to unilaterally start a war without the consent of all the others.

Some miles north of Sempach is the quaint village of Beromünster (973 inhabitants in 1900), with a collegiate church founded in the l0th century and dating, in parts, from the 11th and 12th centuries (fine 17th-century choir stalls and altar frontals), the chapter of secular canons now consisting of invalided priests of the canton of Lucerne: it was in Beromünster that the first dated book was printed (1470) in Switzerland, by care of the canons, while thence came Gering who introduced printing into France.

Of the settled areas, 6.37% is covered with buildings, 0.89% is industrial, 0.22% is classed as special developments, 1.23% is parks or greenbelts and 7.6% is transportation infrastructure.

The historical population is given in the following chart:[9] As of  2013[update], there were a total of 1,878 people employed in the municipality.

[10] In 2014 the crime rate, of the over 200 crimes listed in the Swiss Criminal Code (running from murder, robbery and assault to accepting bribes and election fraud), in Sempach was 42.4 per thousand residents.

In the 2000 census[update] the religious membership of Sempach was as follows: 2,678 (76.9%) were Roman Catholic and 485 (13.9%) were Protestant, with an additional 22 (0.63%) that were of some other Christian faith.

The wettest month is June during which time Sempach receives an average of 148 mm (5.8 in) of precipitation.

The driest month of the year is October with an average of 66 mm (2.6 in) of precipitation over 13.2 days.