install.packages('ggmap')
install.packages('maptools')
install.packages('maps')
install.packages('mapproj')
library(ggmap)
library(maptools)
library(maps)
library(mapproj)

# ACHTUNG:    ändert fill="gray50"  colour="gray50"  color="blue"
#mp <- NULL
mapWorld <- borders("world", colour="gray50", fill="gray50") # create a layer of borders
mp <- ggplot() +   mapWorld
mp <- mp + coord_map(xlim = c(-30, 50),ylim = c(30, 60))

N_Koordinate <- as.numeric(N_Koordinate)
E_Koordinate <- as.numeric(E_Koordinate)

mp <- mp+ geom_point(aes(x=E_Koordinate, y=N_Koordinate) ,color="blue", size=3)
mp