Salzburg's layout and appearance are largely determined by the hills which surround its. On the Altstadt side of the river the Mönchsberg runs into the hill on which the fortress stands on (Festungsberg). Festungsberg and Mönchsberg encircle the old town, which ends at the River Salzach.
Today Salzburg has a population of over 140.000 inhabitants. One steady source of income is the Salzburger Festspiele (Salzburg Festival) taking place each summer. They were first staged in 1920, yet their origins go back to the middle of the 19th century. What started as a mystery play is now one of the most famous festivals in the world, with opera, theatre, orchestral concerts, Mozart matinees, serenades and much more. The Festspiele may be the social and cultural climax of the year, but this doesn't mean that the non-festival months in the calendar are devoid of culture. There are ca. 4.000 various arts events to suit all tastes on offer throughout the year. There are performances at the Salzburg's most-famous puppet theatre, concerts at Hohensalzburg Fortress, at the Residenz and in the marble ballroom at Schloss Mirabell.
Besides festivals, Salzburg is also a seat of learning. After years of discussion and argument - par for the course in Salzburg - on the location of the new university buildings, a solution worthy of Solomon was found; the sciences were given a prestigious new construction on the edge of the Freisaal meadows, one of the city's main parks, whilst the arts and law faculties settled in the palaces in the old town. This academic allocation was one of the reasons Salzburg's Altstadt was made a World Heritage Site. The Republic of Austria and the province of Salzburg spent around 100 million Euros historically restoring the palatial edifices and making the suitable for university use. In doing so, they discovered a number of artistic details which had previously remained hidden, restoring them their former glory.