Ostrý, Mountain summit in Bohemian Uplands, Czechia.

Milleschauer Wostrey (Ostrý, 553 m) is a conical olivine basalt hill in the České středohoří between Milešov, Velemín, Kocourov and Březno, covered in mixed forest. Its steep slopes carry rock faces, frost cliffs with coarse columnar jointing, stone fields and boulder streams; the summit holds the ruins of Ostrý Castle, with remains of a round bastion, gate, walls and a palace torso.

The castle on Ostrý is documented from 1433 as the property of the Kaplirz de Sulewicz family. Its lords abandoned it in 1535 for the Bílý Újezd fortress, and by 1565 it was recorded as deserted. In the 18th century the keep, hall and much of the walls were quarried away.

The German name Scharfenstein, also recorded as Wostrey, appears alongside the Czech Ostrý; the castle is documented in 1433 as the property of the Kaplirz de Sulewicz family. A statue of Saint Anthony of Padua from the mid-18th century stands by the Vlastislav–Milešov road southwest of the summit, a remnant of the Baroque landscape around Milešov.

A blue-marked trail reaches the summit from Březno, Milešov or Kocourov; the upper spiral section is lined with dry-stone walls that once carried parts of the castle defences. The blue route runs from Lovosice via Vchynice and Březno, then descends to the Vlastislav–Milešov road, where a red trail continues to Milešov or Medvědice.

The summit is a conical olivine basalt plug; its steep slopes carry rock faces and frost-riven cliffs with coarse columnar jointing, plus stone fields and boulder streams, some boulders moved by solifluction to the foot. A protected service tree (jeřáb oskeruše) grows on the northeast foot.